Embed Size (px)
Citation preview
International Conference on Organic and
Hybrid Thermoelectrics
January, 29th–February 1st, 2018Valencia, SPAIN
http://icot2018.org
3
Conference Sponsors
5
Welcome to ICOT2018
We welcome you to the International Conference on Organic and Hybrid Thermeoelctrics, which will
be held in Valencia, from the 29th of Jan to the 1st Feb 2017. The use of fossil resources, mainly oil
and carbon, for the production of energy, is one of the main sources of CO2 generation. One of the
bets to favor a cleaner and sustainable environment is the development of thermoelectric devices. If
we pay attention to the expansion of the efficiency in the field or organic or hybrid thermoelectrics,
its increase has been at least three orders of magnitude in ten years. The exchange of information
between scientists working in the field of organic thermoelectrics is essential to have in a few years
thermoelectric devices competitive in price when compared to other clean energy resources.
Prof. Andrés Cantarero
Conference Chairman
7
Organizing Committee
Chair: Andrés Cantarero, University of Valencia, Spain
Co-Chair: Xavier Crispin, Linköping University, Sweden
Mario Culebras, University of Limerick, Ireland
Clara M. Gómez, University of Valencia, Spain
Mauricio M. de Lima Jr., University of Valencia, Spain
Rafael Muñoz-Espí, University of Valencia, Spain
Maria J. Sanchis, Polytechnic University of Valencia, Spain
Marta Carsí, Polytechnic University of Valencia, Spain
International Scientific Committee
Koji Miyazaki, Kyushu Institute of Technology, Japan
Nicolás Agrait, Autonomous University of Madrid, Spain
Kamran Behnia, CNRS & ESPCI, France
Emiliano Bilotti, Queen Mary University of London, UK
Mario Caironi, CNST-IIT, Italy
Mariano Campoy-Quiles, ICMAB-CSIC, Spain
Alexandre Carella, CEA Grenoble, France
Martin Heeney, Imperial College London, UK
Maarit Karppinen, Aalto University, Finnland
Antti J. Karttunen, Aalto University, Finnland
Martijn Kemerink, Linkoping University, Sweden
Kunihito Koumoto, Toyota RCRI, Japan
Colin Lambert, Lancaster University, UK
Marisol Martín-González, IMM-CSIC, Spain
Christian Müller, Chalmers University of Technology, Sweden
Jian Pei, Peking University, China
Jens Paum, Univerity of Würzburg, Germany
Martins Rutkis, University of Latvia, Latvia
Rachel Segalman, UC Santa Barbara, USA
Simon Woodward, University of Nottingham, UK
Monday Jan. 29
8:30-9:00
9:30-9:50
10:00-10:20 10:00-10:20 García-Cañadas (A10) D'Agosta (B10) 10:10-10:30 Laux (A20) Ito (B20)
10:20-10:50 10:20-10:50 10:30-11:00
10:50-11:20 Segalman (I1) Kawai (I2) 10:50-11:20 Kemerink (I7) Shuai (I8) 11:00-11:30 Xu (I13)
11:20-11:40 Aslanl (A1) Whittaker-Brooks (B1) 11:20-11:40 Jang (A11) Liang (B11) 11:30-11:50 Du (A21) Anno (B21)
11:40-12:00 Han (A2) Abargues (B2) 11:40-12:00 Yuan (A12) Zhu (B12) 11:50-12:10 Menon (A22) Marin (B22)
12:00-12:20 Miyazaki (A3) Fujigaya (B3) 12:00-12:20 Kroon (A13) Abdalla (B13) 12:10-12:30 Yan (A23) Rutkis (B23)
12:20-12:40 Wijeratne (A4) 12:20-12:40 Andrei (A14) Dalkiranis (B14) 12:30:12:50 Kanahashi (A24) Pudzs (B24)
12:40:13:00 Selezneva (A5) Zhao (B5) 12:40:13:00 Zapata-Arteaga (A15) Kandhasamy (B15) 12:50-13:10 Qu (A25) Chen (B25)
13:00-14:30 13:00-14:30 13:10-14:30
14:30-15:00 Blackburn (I3) Pflaum (I4) 14:30-15:00 Katz (I9) Di (I10) 14:30-15:00 Yee (I15) Zotti (I16)
15:00-15:20 Krahl (A6) Culebras (B6) 15:00-15:20 Wan (A16) Kojima (B16) 15:00-15:20 Yang (A26) Bharti (B26)
15:20:15:40 Fenwick (A7) Horike (B7) 15:20:15:40 Muñoz-Espí (A17) Kiyota (B17) 15:20:15:40 Goñi (A27) Xu (B27)
15:40-16:00 Jiao (A8) Nakano (B8) 15:40-16:00 Rösch (B18) 15:40-16:00 Massetti (A28) Tkachov (B28)
16:00-16:30 16:00-16:30 16:00-16:30
16:30-16:50 Kumar (A9) Nonoguchi (B9) 16:30-16:50 Mori (A19) Jurado (B19) 16:30-17:00 Agrait (I17)
16:50-17:20 Statz (I5) Müller (I6) 16:50-17:20 Fabiano (I11) Campoy-Quiles (I12) 17:00-17:30
20:00-23:30
17:20-19:00
9:00-10:00
Coffee Break
Coffee Break Coffee Break
Closure16:30 h Registration
Arrival
9:00-10:00
Conference Banquet
18:00 h Welcome
Reception (with special
luthier demonstration)
Poster session I
Tourist visit
Poster session II17:20-19:00
19:00-22:00
8:30-9:30
Shevlin (S2)
Coffee Break
Lunch break Lunch break
ICOT 2018 – CONFERENCE SCHEDULE
Coffee Break
Coffee Break
Lunch break
Chabinyc (PL2)
Toshima (PL3)
Opening Ceremony
Marx (S1)
Grunlan (PL1)
Tuesday Jan. 30 Wednesday Jan. 31 Thursday Feb. 1
Biniek (I14)
11
ICOT 2018 – Program
Monday, January 29, 2018
16:30–18:00 Registration
18:00–21:00
Welcome Reception Location: ADEIT Terrace During the Welcome Reception there will be a live demonstration by the guitar luthier Vicente Carrillo, who will show us how a classic guitar is built.
Tuesday, January 30, 2018
8:30–9:00 Opening Ceremony
Chair: Michael L. Chabinyc
9:00–10:00 PL1 PLENARY LECTURE Jaime C. Grunlan (Texas A&M Univ., USA) “High Power Factor, Completely Organic Thermoelectric Nanocoatings for Flexible Films and Textiles”
10:00–10:20 S1 Hans-W. Marx (Linseis, Germany) “Measurement System for Thermophysical Properties of Thin Films in a Broad Temperature Range”
10:20–10:50 Coffee Break
Room A Chair: Alejandro Goñi
Room B Chair: Shannon Lee
10:50–11:20 I1
INVITED LECTURE Rachel A. Segalman (UCSB, USA) “Increasing the Power Factor of PEDOT:PSS through Selective Blending of Protic and Aprotic Ionic Liquids”
I2
INVITED LECTURE Tsuyoshi Kawai (NAIST, Japan) “Stable n-type Single Walled Carbon Nanotubes with New Organic Doping Reagents for Future Thermoelectric Conversion”
11:20–11:40 A1 Silas Aslan (KIT, Germany) “Nanostructured Organic Thermoelectrics: PEDOT Nanowires for Printed Devices”
B1 Luisa Whittaker-Brooks (Univ. Utah, USA) “Manipulating the Thermoelectric and Spin Properties of Polymeric Systems”
11:40–12:00 A2
Shaobo Han (Linköping Univ., Sweden) “Thermoelectric Polymer Aerogels for Pressure–Temperature Sensing Applications”
B2 Rafael Abargues (Univ. Valencia, Spain) “In-situ Synthesized Conducting Nanocomposite: A Step Towards Printable Polymer Thermoelectrics”
12:00–12:20 A3 Koji Miyazaki (Kyutech, Japan) “Printed Flexible Thermoelectric Device of the Organic/Inorganic Composite”
B3
Tsuyohiko Fujigaya (Kyushu Univ., Japan) “Study of Stability Mechanism of Air-Stable n-type Single-walled Carbon Nanotube Films Doped with Benzimidazole Derivative”
12:20–12:40 A4
Kosala Wijeratne (Linköping Univ., Sweden) “PEDOT–PSS Electrodes for Thermogalvanic Cells”
B4 Chang-Soo Lee (Chungnam Natl. Univ., South Korea) “Mechanically Optimized Design for the Reversible Self-Bending Soft Microstructure”
12:40–13:00 A5
Ekaterina Selezneva (Univ. Cambridge, UK) “An Apparatus for Accurate Measurements of Thermal Conductivity”
B5 Dan Zhao (Linköping Univ. Sweden) “Ionic Thermoelectric Effect and Devices”
13:00–14:30 Lunch Break
12
Room A Chair: Rachel A. Segalman
Room B Chair: Luisa Whittaker-Brooks
14:30–15:00 I3
INVITED LECTURE Jeffrey Blackburn (NREL, USA) “Large n- and p-Type Thermoelectric Power Factors from Highly Enriched Semiconducting Single-Walled Carbon Nanotube Networks”
I4 Candidates for
INVITED LECTURE Jens Pflaum (Uni Würzburg, Germany) “Organic Metals: Potential Thermoelectrics”
15:00–15:20 A6 Fabian Krahl (Aalto Univ., Finland) “Thermal Conductivity in Layer-Engineered Inorganic–Organic Thin Films”
B6 Mario Culebras (Univ. Limerick, Ireland) “Carbon-Based Materials and Nanocomposites for Thermoelectric Applications”
15:20–15:40 A7
Oliver Fenwick (QMUL, UK) “Morphological Tuning of Thermal Conductivity in Halide Perovskite Thin Films”
B7
Shohei Horike (Kobe Univ., Japan) “Highly Stable n-Type Carbon Nanotubes via Simple Vinyl Polymer Doping for Flexible Thermoelectric Generators”
15:40–16:00 A8 Fei Jiao (Linköping Univ., Sweden) Ionic Thermoelectric Paper B8
Motohiro Nakano (NAIST, Japan) “Enhancing the Thermoelectric Properties of Single-walled Carbon Nanotubes by Polyelectrolytes”
16:00–16:30 Coffee Break
16:30–16:50 A9 Pawan Kumar (IMRE, Singapore) “Probing Energy-Dependent Scattering in CuTe:PEDOT Hybrid Thermoelectric Films”
B9 Yoshiyuki Nonoguchi (NAIST, Japan) “Dual Mode Thermoelectric Transport in a Semiconducting Carbon Nanotube Film”
16:50–17:20 I5
INVITED LECTURE Martin Statz (Univ. Cambridge, UK) “On the Manifestation of Ellectron–Electron Interactions in the Thermoelectric Response of Semicrystalline Conjugated Polymers with Low Energetic Disorder”
I6 INVITED LECTURE Christian Müller (Chalmers Univ. Technol., Sweden) “Heat Harvesting Thermoelectric Textiles”
17:20–19:00 Poster Session I
A Best Poster Award will be sponsored by Nature Publishing Group
19:00–22:00 Tourist Visit
13
Wednesday, January 31, 2018
Chair: Jaime C. Grunlan
08:30–09:30 PL2
PLENARY LECTURE Michael L. Chabinyc (UC Santa Barbara, USA) “Thermoelectric Properties of Organic Polymers”
09:30–09:50 S2
Stephen Shevlin (Associate Editor of Nature Materials) “Publishing in Nature Research Journals”
09:50–10:00 Short break for room splitting
Room A Chair: Kawai Tsuyoshi
Room B Chair: Mariano Campoy-Quiles
10:00–10:20 A10
Jorge García-Cañadas (Univ. Jaume I, Spain) “More than 2 Times Improvement in the Power Factor of Thermoelectric Films using Liquid Electrolytes”
B10
Roberto d'Agosta (Centro Joxe Mari Korta, Spain) “Ab Initio Modelling of Thermoelectric Transport in Simple Polymers”
10:20–10:50 Coffee Break
10:50–11:20 I7
INVITED LECTURE Martijn Kemerink (Linköping Univ., Sweden) “Morphology Control and Density of States Engineering Give Very High Seebeck Coefficients in Organic Thermoelectric Blends”
I8
INVITED LECTURE Zhigang Shuai (Tsinghua Univ., China) “Computational Design of Thermoelectric Polymers with Large Figure of Merits”
11:20–11:40 A11
Jaegyu Jang (Seoul National Univ., South Korea) “Water-Resistant Polymer Organic Thermoelectric Devices”
B11
Ziqi Liang (Fudan Univ., China) “Development of n-Type Metal Nonowire/Polymer Thermoelectric Nanocomposites with Large Power Factor”
11:40–12:00 A12
Dafei Yuan (CAS, China) “Efficient Solution-Processed n-Type Small-Molecule Thermoelectric Materials Achieved by Precisely Regulating Energy Level of Organic Dopants”
B12
Xiaozhang Zhu (CAS, China) “Efficient Solution-Processed n-Type Small-Molecule Thermoelectric Materials Achieved by Precisely Regulating Energy Level of Organic Dopants”
12:00–12:20 A13
Renee Kroon (Chalmers Univ. Technol., Sweden) “Polar Side Chains Enhance Processability, Electrical Conductivity, and Thermal Stability of a Molecularly p-Doped Polythiophene”
B13
Hassan Abdalla (Linköping Univ., Sweden) “Coulomb Interactions Dominate Charge and Energy Transport in Organic Field Effect Transistors”
12:20–12:40 A14 Virgil Andrei (HU Berlin, Germany) “Multi-Layering in Thin Film Organic Thermoelectrics: The Hidden Gem”
B14 Gustavo G. Dalkiranis (UAB, Spain) “In-Plane Thermal Conductivity of Organic Films using the 3ω-Volklein Method”
12:40–13:00 A15
Osnat Zapata-Arteaga (ICMAB-CSIC, Spain) Optimization of Polymer Thermoelectrics via Doping Gradient
B15
Sathiyaraj Kandhasamy (NTNU, Norway) "Molten Carbonate Electrolyte Based Thermocells for High Temperature Waste Heat Recovery hexylthiophene) by Regulating the Molecular Structure”
13:00–14:30 Lunch Break
14
Room A Chair: Jens Pflaum
Room B Chair: Roberto d’Agosta
14:30–15:00 I9
INVITED LECTURE Howard Katz (John Hopkins Univ., USA) “Polymer-Dopant Synergies for Increased Hole and Electron Contributions to Thermoelectric Power Factor”
I10
INVITED LECTURE Chong-an Di (CAS, China) “Electric Field Modulations Assisted Development of High Performance n-Type Organic Thermoelectric Materials”
15:00–15:20 A16
Kening Wan (Queen Mary Univ. London, UK) “Flexible Self-powered Sensors Using Organic Thermoelectric Effect”
B16
Hirotaka Kojima (NAIST, Japan) “Recent Progress on Understanding the Origin of Giant Seebeck Effect in Organic Small Molecules”
15:20–15:40 A17
Rafael Muñoz-Espí (Univ. Valencia, Spain) “Conducting Polymer Nanoparticles by Miniemulsion Polymerization: Pros and Cons for Thermoelectric Applications”
B17
Yasuhiro Kiyota (Tokio Inst. Technol., Japan) Low-Temperature Characteristics of a Thermoelectric Generator using Organic Charge-Transfer Salts
15:40–16:00 A18 B18 Andres Rösch (KIT, Germany) “Print Layout Design for Roll-to-Roll Produced Thermoelectric Generators”
16:00–16:30 Coffee Break
16:30–16:50 A19
Takao Mori (NIMS, Japan) “Hybrid Effect for Thermoelectric Enhancement and Development of Flexible Modules”
B19
José Piers Jurado (ICMAB-CSIC, Spain) “Organic Solar Thermoelectric Generators”
16:50–17:20 I11
INVITED LECTURE Simone Fabiano (Linköping Univ., Sweden) “N-doped Conducting Polymers for Thermoelectrics”
I12
INVITED LECTURE Mariano Campoy-Quiles (ICMAB-CSIC, Spain) “Simultaneous Determination of the Thermal Conductivity and Thermal Boundary Resistance in Supported Thin Organic Films”
17:20–19:00 Poster Session I
A Best Poster Award will be sponsored by Nature Publishing Group
20:00–23:30 Conference Banquet
Location: Hotel Astoria
15
Thursday, February 1, 2018
Chair: Simon Woodward
09:00–10:00 PL3 PLENARY LECTURE Noaki Toshima (Tokio Univ. of Science, Japan) “Organic Hybrid Thermoelectric Materials Involving Nanomaterials”
10:00–10:10 Short break for room splitting
Room A Chair: Jorge García-Cañada
Room B Chair: Emiliano Bilotti
10:10–11:30 A20 Edith Laux (HES-SO, Switzerland) “Temperature Dependence of Seebeck Coefficient in Ionic Liquids”
B20 Masahiro Ito (Tokio Univ. of Sci., Japan) “Modulation of thermoelectric of PEDOT/PSS by carrier injection with ferroelectrics”
10:30–11:00 Coffee Break
11:00–11:30 I13
INVITED LECTURE Wei Xu (CAS, China) “Promising Polymeric Thermoelectric Thin Films of Poly(Ni-ethylenetetrathiolate) and Polythiophene Prepared by Electrochemical Deposition”
I14
11:30–11:50 A21
Yong Du (Shanghai Inst. of Technol., China) “Flexible PEDOT:PSS & Polypyrrole nanoparticles Co-coated Cotton Fabric Thermoelectric Films”
B21
Hiroaki Anno (Tokyo Univ. of Science, Japan) In-Plane Thermoelectric Properties of Hybrid Films Consisting of a Nano Titanium Disulfide, Conducting Polymer PEDOT−PSS, and Carbon Nanotubes
11:50–12:10 A22 Akanksha K. Menon (Georgia Tech, USA) “Metallo-Organic Polymers and Devices for Thermoelectric Energy Harvesting”
B22 Giovanni Martin (Aalto Univ., Finland) “Flexible thermoelectric device based on ALD-grown ZnO and ZnO:benzene thin films”
12:10–12:30 A23 Hu Yan (Zhengzhou Univ., China) “Preparation and Thermoelectric Properties of PEDOT/PSS-HNTs Hybrid Thin Films”
B23 Martins Rutkis (Univ. Latvia, Latvia) “Development of Thin Film Organic TE Generator based on tetrathiotetracene”
12:30–12:50 A24
Kaito Kanahashi (Nagoya Univ., Japan) “Thermoelectric Properties of Organic Donor-Acceptor Copolymers Investigated by Electrolyte Gating Tetrathiotetracenes Thin Films”
B24
Kaspars Pudzs (Univ. Latvia, Latvia) “Thermoelectrical Properties of 2- and 2,8-Substituted”
12:50–13:10 A25
Sanyin Qu (CAS, China) “Investigating on the Intrinsic Charge Transport in Poly(3-Hexylthiophene) by Regulating the Molecular Structure”
B25
Yanling Chen (CAS, China) “Enhanced Thermoelectric Performance of Copper Phthalocyanine by Iodine Doping”
13:10–14:30 Lunch Break
INVITED LECTURE Laure Biniek (Univ. Strasbourg/CNRS) “Fabrication of Highly Oriented and Crystalline Conducting Polymer Films with Anisotropic Charge Transport and Thermoelectric Properties”
16
Room A Chair: Andrés Cantarero
Room B Chair: Jian Pei
14:30–15:00 I15
INVITED LECTURE Shannon Yee (Georgia Tech, USA) “Metal Coordinated Polymer Thermoelectrics and Devices”
I16
INVITED LECTURE Linda A. Zotti (Auton. Univ. Madrid, Spain) “Direct Observation of Peltier Cooling in Molecular Junctions”
15:00–15:20 A26
Chi-Yuan Yang (Peking Univ., China) “Boost the N-Type Thermoelectric Performance of Diketopyrrolopyrrole-Based Polymers Through Backbone Engineering”
B26
Meetu Bharti (Bhabha Atomic Res. Center, India) “Conducting polymers: Opening new avenues in room temperature thermoelectric applications”
15:20–15:40 A27
Alejandro Goñi (ICMAB-CSIC/ICREA, Spain) “The Influence of Dynamic Disorder on the Vibrational and Thermal Properties of Hybrid Perovskites”
B27
Ling Xu (Huazhong Univ. Science and Technology, China)
“Enhancing Thermoelectric Performance Using the Excited State by Photoexcitation base on the organic semiconductor materials”
15:40–16:00 A28 Matteo Massetti (IIT, Italy) “Microfabrication of an Organic TEG with Vertical Architecture”
B28 Roman Tkachov (TU Dresden / Fraunhofer, Germany) “Synthesis of n-type nickel-tetrathiooxalate polymer with improved and reproducible thermoelectric characteristics”
16:00–16:30 Coffee Break
16:30–17:00 I17
INVITED LECTURE Nicolás Agrait (Auton. Univ. Madrid, Spain) “Quantum Thermopower in Molecular Junctions”
17:00–17:30 Closure
ABSTRACTS
19
INDEX
Plenary Lectures
PL1: High Power Factor, Completely Organic Thermoelectric Nanocoatings for Flexible Films
and Textiles
Chungyeon Cho , Choongho Yu , Jaime C. Grunlan ............................................................................... 29
PL2: Thermoelectric Properties of Organic Polymers
Michael L. Chabinyc ..................................................................................................................................... 30
PL3: Organic Hybrid Thermoelectric Materials Involving Nanomaterials
Naoki Toshima .............................................................................................................................................. 31
Invited Lectures
I1: Increasing the Power Factor of PEDOT:PSS through Selective Blending of Protic and
Aprotic Ionic Liquids
Rachel A. Segalman ...................................................................................................................................... 35
I2: Stable N-type Single Walled Carbon Nanotubes with New Organic Doping Reagents for
Future Thermoelectric Conversion
Tsuyoshi Kawai ............................................................................................................................................. 36
I3: Large n- and p-type Thermoelectric Power Factors from Highly Enriched Semiconducting
Single-walled Carbon Nanotube Networks
I4: Organic Metals: Potential Candidates for Thermoelectrics
Alexander Steeger, Florian Huewe, Kalina Kostova, Laurence Burroughs, Irene Bauer, Peter
Strohriegl, Vladimir Dimitrov, Simon Woodward and Jens Pflaum............................................................. 38
I5: On the Manifestation of Electron-Electron Interactions in the Thermoelectric Response
of Semicrystalline Conjugated Polymers with Low Energetic Disorder
M. Statz, D. Venkateshvaran, H. Sirringhaus and R. Di Pietro .................................................................... 39
I6: Heat Harvesting Thermoelectric Textiles
Christian Müller ............................................................................................................................................. 40
I7: Morphology Control and Density of States Engineering Give Very High Seebeck Coefficients
in Organic Thermoelectric Blends
Guangzheng Zuo, Xianjie Liu, Mats Fahlman and and Martijn Kemerink ................................................... 41
I8: Computational design of thermoelectric polymers with large figure of merits
Zhigang Shuai, Dong Wang, Wen Shi, Yajing Sun .................................................................................... 42
I9: Polymer-Dopant Synergies for Increased Hole and Electron Contributions to
Thermoelectric Power Factor
Howard E. Katz, Hui Li, and Xingang Zhao ................................................................................................. 43
I10: Electric Field Modulations Assisted Development of High Performance n-type
Organic Thermoelectric Materials
Chong-an Di, Ye Zou, Daoben Zhu .............................................................................................................. 44
I11: N-doped conducting polymers for thermoelectrics
Jeffrey Blackburn ........................................................................................................................................... 37
20
Simone Fabiano ............................................................................................................................................ 45
I12: Simultaneous determination of the thermal conductivity and thermal boundary resistance
in supported thin organic films
Xabier Rodríguez-Martínez, Osnat Zapata Arteaga, Aleksandr Perevedentsev, Alejandro R.
Goñi, Sebastian Reparaz, Mariano Campoy Quiles ...................................................................................... 46
I13: Promising Polymeric Thermoelectric Thin Films of Poly(Ni- ethylenetetrathiolate)
and Polythiophene Prepared by Electrochemical deposition
Wei Xu, Yimeng Sun, Chong-an Di, Daoben Zhu ....................................................................................... 47
I15: Metal Coordinated Polymer Thermoelectrics and Devices
Shannon Yee ................................................................................................................................................ 49
I16: Direct Observation of Peltier Cooling in Molecular Junctions
Longji Cui, Ruijiao Miao, Kun Wang, Dakotah Thompson, Linda A. Zotti, Juan Carlos Cuevas, Edgar
Meyhofer, Pramod Reddy ................................................................................................................................ 50
I17: Quantum Thermopower in Molecular Junctions
Nicolás Agrait .............................................................................................................................................. 51
Oral ContributionsA1: Nanostructured organic thermoelectrics-PEDOT nanowires for printed devices
Verena Schendel, Silas Aslan, André Gall, Andrés Roesch, Matthias Hecht, Frederick Lessman and Uli
Lemmer ........................................................................................................................................................ 55
A2: Thermoelectric Polymer Aerogels for Pressure–Temperature Sensing Applications
Shaobo Han, Fei Jiao, Zia Ullah Khan, Jesper Edberg, Simone Fabiano, and Xavier Crispin .................... 56
A3: Printed Flexible Thermoelectric Device of the Organic/Inorganic composite
Koji Miyazaki, Tomohide Yabuki, Laurent Tranchant, and Kunihisa Kato ................................................ 57
A4: PEDOT-PSS electrodes for Thermogalvanic Cells
Kosala Wijeratne, Ujwala Ail, Robert Brooke, Mikhail Vagin, Xavier Crispin .............................................. 58
A5: An apparatus for accurate measurements of thermal conductivity
Ekaterina Selezneva, Pablo Díaz-Chao, Andres Muniz-Piniella, Alexandre Cuenat, Henning
Sirringhaus................................................................................................................................................... 59
A6: Thermal conductivity in layer-engineered inorganic-organic thin films
Fabian Krahl, Ashutosh Giri, John P. Tomko, Tommi Tynell, John P. Hopkins, Maarit Karppinen..........60
A7: Morphological tuning of thermal conductivity in halide perovskite thin films
Tianjun Liu, Thibault Degousée, Sinclair Ryley Ratnasingham, Pritesh Ravji Varsani, Joe
Briscoe, Martyn McLachlan, and Oliver Fenwick. ..................................................................................... 61
I14: Fabrication of highly oriented and crystalline conducting polymer films with
anisotropic charge transport and thermoelectric properties
Martin Brinkmann, Amer Hamidi-Sakr, Vishnu Vijayakumar, Laure Biniek, Patrick Lévêque, Jean-
Louis Bantignies, David Maurin, Nicolas Lecler......................................................................................... 48
21
A8: Ionic Thermoelectric Paper
Fei Jiao, Ali Naderi, Dan Zhao, Joshua Schlueter, Maryam Shahi, Jonas Sundström, Hjalmar
Granberg, Jesper Edberg, Ujwala Ail, Joseph Brill, Tom Lindström, Magnus Berggren and Xavier
Crispin......................................................................................................................................................... 62
A9: Probing energy-dependent scattering in CuTe:PEDOT hybrid thermoelectric films
Pawan Kumar, Eddy Zaia, DV Maheswar Repaka, Jeff Urban, Kedar Hippalgaonkar ....................................... 63
A10: More than 2 times improvement in the power factor of thermoelectric films using
liquid electrolytes
L. Márquez-García, B. Beltrán-Pitarch and J. García-Cañadas .................................................................. 64
A11: Water-resistant Polymer Organic Thermoelectric Devices
Jae Gyu Jang, Yongjun Jeon, Jong-In Hong, and Sung Hyun Kim ........................................................... 65
A12: A New Type of Conducting Polymers for Thermoelectric Application
Dafei Yuan, Liyao Liu, Wei Xu, Xiaozhang Zhu, and Daoben Zhu .................................................... 66
A13: Polar Side Chains Enhance Processability, Electrical Conductivity, and Thermal Stability of
a Molecularly p-Doped Polythiophene
Renee Kroon, David Kiefer, Dominik Stegerer, Liyang Yu, Michael Sommer, and Christian
Müller ......................................................................................................................................................... 67
A14: Multi-layering in thin film organic thermoelectrics: the hidden gem
Virgil Andrei, Kevin Bethke, Klaus Rademann ......................................................................................... 68
A15: Optimization of polymer thermoelectrics via doping gradient
Osnat Zapata-Arteaga, Bernhard Dörling, and Mariano Campoy-Quiles ................................................. 69
A16: Flexible Self-powered Sensors Using Organic Thermoelectric Effect
Kening Wan, Prospero Taroni Junior, Zilu Liu, Bob C Schroeder and Emiliano Bilotti ......................... 70A17: Conducting Polymer Nanoparticles Prepared by Miniemulsion Polymerization: Pros and
Cons for Thermoelectric Applications
Mario Culebras, José F. Serrano-Claumarchirant, Juan F. Ferrer-Crespo, Amparo Sánchez-Soler,
Maria J. Sanchis, Andrés Cantarero, Clara M. Gómez, Rafael Muñoz-Espí ............................................ 71
A19: Hybrid Effect for Thermoelectric Enhancement and Development of Flexible Modules
Takao Mori and Norifusa Satoh ................................................................................................................ 72
A20: Temperature Dependence of Seebeck Coefficient in Ionic Liquids
Laure Jeandupeux, Edith Laux, Stefanie Uhl, Herbert Keppner1 ............................................................... 73
A21: Flexible PEDOT:PSS & Polypyrrole nanoparticles Co-coated Cotton Fabric Thermoelectric Films
Yong Du, Biplab Paul, and Per Eklund ..................................................................................................... 74
A22: Metallo-Organic Polymers and Devices for Thermoelectric Energy Harvesting
Akanksha K. Menon, Rylan Wolfe, Kiarash Gordiz, Hend Elmoughni, John R. Reynolds and Shannon K.
Yee............................................................................................................................................................. 75
A23: Preparation and Thermoelectric Properties of PEDOT/PSS-HNTs Hybrid Thin Films
Hu Yan ....................................................................................................................................................... 76
A24: Thermoelectric properties of organic donor-acceptor copolymers investigated by electrolyte gating
22
Kaito Kanahashi, Naoya Takekoshi, Yong-Young Noh, Hiromichi Ohta, Hisaaki Tanaka and Taishi
Takenobu................................................................................................................................................... 77
A25: Investigating on the Intrinsic Charge Transport in Poly(3- hexylthiophene) by Regulating
the Molecular Structure
Sanyin Qu, Qin Yao and Lidong Chen ...................................................................................................... 78
A26: Boost the N-Type Thermoelectric Performance of Diketo- pyrrolopyrrole-Based
Polymers Through Backbone Engineering
Chi-Yuan Yang, Yi-Fan Ding ,
Wen-Long Jin,
Chong-An Di,
Jie-Yu Wang, and Jian Pei.................... 79
A27: The influence of dynamic disorder on the vibrational and thermal properties of hybrid perovskites
Aurélien M. A. LeguY, Xabier Rodríguez-Martínez, Adrián Francisco López, Jarvist M. Frost, Jonathan
Skelton, Federico Brivio, Bethan Charles, Oliver J. Weber, Anuradha Pallipurath, M. Isabel Alonso,
Mariano Campoy-Quiles, Mark T. Weller, Jenny Nelson, Aron Walsh, Piers R.F. Barnes
& Alejandro R. Goñi ................................................................................................................................. 80
A28: Microfabrication of an Organic TEG with vertical architecture
Matteo Massetti, Marco Cassinelli, and Mario Caironi............................................................................. 81
B1: Manipulating the thermoelectric and spin properties of polymeric systems
Jonathan Ogle, Mandefro Yehulie,
Christoph Boehme,
Luisa Whittaker-Brooks ................................... 82
B2: In-situ synthesized conducting Nanocomposite - A step towards printable
polymer thermoelectrics
Rafael Abargues, Pedro J. Rodríguez-Cantó, Alvaro Seijas, Eduardo Aznar, Clara Gómez,Andrés Cantarero, Juan P. Martínez-Pastor............................................................................................. 83
B3: Study of Stability Mechanism of Air-Stable n-type Single-walled Carbon Nanotube Films
Doped with Benzimidazole Derivative
Yuki Nakashima, Wenxin Huang, Aleksandar Staykov, and Tsuyohiko Fujigaya................................... 84
B4: (cancelled)
B5: Ionic thermoelectric effect and devices
Dan Zhao, Zia Ullah Khan, Simone Fabiano, Xavier Crispin .................................................................. 86
B6: Carbon based materials and nanocomposites for thermoelectric applications
Mario Culebras, Maurice N. Collins, Eric Dalton, Clara M. Gómez and Andrés Cantarero ................... 87
B7: Highly Stable N-Type Carbon Nanotubes via Simple Vinyl Polymer Doping for
Flexible Thermoelectric Generators
Shohei Horike, Tatsuya Fukushima, Takeshi Saito, Yasuko Koshiba and Kenji Ishida.......................... 88
B8: Enhancing the Thermoelectric Properties of Single-walled Carbon Nanotubes by Polyelectrolytes
Motohiro Nakano, Takuya Nakashima, Tsuyoshi Kawai and Yoshiyuki Nonoguchi ............................. 89
B9: Dual Mode Thermoelectric Transport in a Semiconducting Carbon Nanotube Film
Yoshiyuki Nonoguchi, Chigusa Goto, Tsuyoshi Kawai ........................................................................... 90
B10: Ab initio modelling of thermoelectric transport in simple polymers
Roberto d’Agosta ..................................................................................................................................... 91
B11: Development of n-Type Metal Nanowire/Polymer Thermoelectric Nanocomposites with Large
23
Power Factor
Yani Chen, Minhong He, Guillermo C. Bazan, Jun Zhou and Ziqi Liang ............................................. 92
B12: Efficient Solution-Processed n-Type Small-Molecule Thermoelectric Materials Achieved
by Precisely Regulating Energy Level of Organic Dopants
Dafei Yuan, Dazhen Huang, Cheng Zhang, Ye Zou, Chong-an Di, Xiaozhang Zhu, Daoben Zhu.........93
B13: Coulomb Interactions Dominate Charge and Energy Transport in Organic Field
Effect Transistors
Hassan Abdalla, Simone Fabiano, Martijn Kemerink................................................................................. 94
B14: In-plane thermal conductivity of organic films using the 3ω- Volklein method
G. G. Dalkiranis, I. Ruiz-Cózar, J. Ràfols-Ribé, M. Gonzalvez-Silveira, Ll. Abad, A. F. Lopeandía,
J. Rodríguez-Viejo. .................................................................................................................................... 95
B15: Molten Carbonate Electrolyte Based Thermocells for High Temperature Waste
Heat Recovery
Sathiyaraj Kandhasamy, Signe Kjelstrup, Asbjørn Solheim and Geir Martin Haarberg ........................... 96
B16: Recent Progress on Understanding the Origin of Giant Seebeck Effect in Organic
Small Molecules
Hirotaka Kojima, Ryo Abe, Takanobu Takeuchi, Satoshi Inoue, Seiichiro Izawa, Mitsuru Kikuchi,
Masahiro Hiramoto, Yumi Yakiyama,
Hidehiro Sakurai,
Masakazu Nakamura .................................. 97
B17: Low-temperature characteristics of a thermoelectric generator using organic charge-
transfer salts
Yasuhiro Kiyota, Tadashi Kawamoto and Takehiko Mori ........................................................................ 98
B18: Print Layout Design for Roll-to-Roll Produced Thermoelectric Generators
Andres Rösch, André Gall, Matthias Hecht, Silas Aslan, Frederick Lessmann, Verena Schendel,
Uli Lemmer ............................................................................................................................................... 99
B19: Organic Solar Thermoelectric Generators
José Piers Jurado , Osnat Zapata-Arteaga, Bernhard Dörling and Mariano Campoy-Quiles................. 100
B20: Modulation of thermoelectric of PEDOT/PSS by carrier injection with ferroelectrics
Masahiro Ito, Kazuya Okamoto, Takashi Nakajima, Hiroaki Anno, Takahiro Yamamoto..................... 101
B21: In-plane Thermoelectric Properties of Hybrid Films Consisting of a Nano Titanium Disulfide,
Conducting Polymer PEDOT−PSS, and Carbon Nanotubes
Hiroaki Anno and Kazuya Okamoto ....................................................................................................... 102
B22: Flexible thermoelectric device based on ALD-grown ZnO and ZnO:benzene thin films
Marin Giovanni, Karppinen Maarit ......................................................................................................... 103
B23: Development of Thin Film Organic TE Generator based on tetrathiotetracene
Martins Rutkis, Kaspars Pudzs, Aivars Vembris, Simon Woodward................................................... 104
B24: Thermoelectrical Properties of 2- and 2,8-Substituted Tetrathiotetracenes thin films
Kaspars Pudzs, Martins Rutkis, Janis Uzulis, Aivars Vembris, Simon Woodward ................................ 105
B25: Enhanced Thermoelectric Performance of Copper Phthalocyanine by Iodine Doping
Yanling Chen, Sanyin Qu , Qin Yaoa, Lidong Chen ................................................................................ 106
B26: Conducting polymers: Opening new avenues in room temperature thermoelectric
applications
24
Meetu Bharti, Ajay Singh, K. P. Muthe, S. C. Gadkari, D. K. Aswal .................................................. 107
B27: Study the thermoelectric properties under photoexcitation base on the CH3NH3PbI3
polycrystalline thin films
Ling Xu， Ping Wu , Yan Xiong ........................................................................................................... 108
B28: Synthesis of n-type nickel-tetrathiooxalate polymer with improved and
reproducible thermoelectric characteristics
Roman Tkachov, Lukas Stepien, Robert Grafe, Olga Guskova, Anton Kiriy, Heiko Reith,
Christoph Leyens ................................................................................................................................... 109
PostersP1: 5,5’-Diazaisoindigo: an Electron-Deficient Building Block for Donor–Acceptor
Conjugated Polymers
Yang Lu, Jie-Yu Wang, Jian Pei............................................................................................................ 113
P2: Study the thermoelectric properties under photoexcitation based on the
CH3NH3PbI3 polycrystalline thin films
,Ling Xu Ping Wu, Yan Xiong ........................................................................................................114
P3: An experimental study on thermoelectric properties of graphene modulated by ferroelectric gate
FET
Yutaro Fujisaki, Hikaru Horii, Masahiro Ito, Satoru Konabe, Takahiro Yamamoto, Yoichiro
Hashizume, Takashi Nakajima, and Soichiro Okamura .......................................................................... 115
P4: On the Manifestation of Electron-Electron Interactions in the Thermoelectric Response
of Semicrystalline Conjugated Polymers with Low Energetic Disorder
M. Statz, D. Venkateshvaran, H. Sirringhaus and R. Di Pietro ............................................................... 116
P5: Analytical approach to thermoelectric properties of carbon nanotube thin film using a
random graph theory
Yoichiro Hashizume, Masaaki Tsukuda, Takahiro Yamamoto, Takashi Nakajima, and Soichiro
Okamura .................................................................................................................................................. 117
P6: Facile Fabrication of PEDOT:PSS/SWCNT Composite Film with High Thermoelectric Properties
Ichiro Imae, Lu Zhang, and Yutaka Harima ........................................................................................... 118
P7: Thermoelectric Properties of Solution-Processed n-Doped Ladder-Type Conducting Polymers
Suhao Wang, Magnus Berggren, Xavier Crispin, Daniele Fazzi, and Simone Fabiano ........................ 119
P8: High Power Factor, Completely Organic Thermoelectric Nanocoatings for Flexible Films
and Textiles
Chungyeon Cho, Choongho Yu, JaimeC.Grunlan................................................................................. 120
P9: Synthesis, Characterization, and Thermoelectric Performance of π-Conjugated Polymers with
Metal-Bis(dithiolene) Units
Nana Toyama, Kazuki Ueda, Mika Oku, Masahiro Muraoka, and Michihisa Murata .......................... 121
P10: Thermoelectric properties of a semi conducting compound CoSb3 doped with Sn and Se
Mohamed Chitroub ................................................................................................................................ 122
P11: Effects of CNT Type, Processing, and Doping on Thermoelectric Performance
25
Bernhard Dörling, Osnat ZapataArteaga and Mariano CampoyQuiles ....................................................... 123
P12: Evaluation of conductivity L11 and thermoelectric coefficient L12 by current-voltage measurement
Takashi Nakajima, Takahiro Yamamoto, Yoichiro Hashizume, Masahiro Ito, Takashi Utsu,
Keishi Nishio, Hidetoshi Fukuyama, and Soichiro Okamura......................................................... ..... 124
P13: Investigation of Contact Resistance in Organic Thermoelectric Devices
Juhyung Park, Jaeyun Kim, Jeonghun Kwak .............................................................................. ...... 125
P14: Half-metallic completely compensated ferrimagnets in Cr doped BaP
A. Bouabca, H.Rozale, Wang X.T, A.Sayade ................................................................................. ... 126
P15: High pressure study of vibrational properties of methylammonium lead iodide perovskites
Adrian Francisco López, Bethan Charles, Oliver Weber, M. Isabel Alonso, Miquel Garriga, Mariano
Campoy-Quiles, Mark Weller, Alejandro R. Goñi ............................................................................... 127
P16: Investigation of Contact Resistance in Organic Thermoelectric Devices
Juhyung Park, Jaeyun Kim, Jeonghun Kwak........................................................................................ 128
P17: Improvement of Thermoelectric properties of polymeric PEDOT:Tos based devices
Geoffrey Prunet, Eric Cloutet, Guillaume Fleury, Eleni Pavlopoulou, Stephane Grauby, Stefan
Dilhaire and Georges Hadziioannou .................................................................................................... 129
P18: Preparation of colloidal silica using the biomimetic synthesis
Kyoung-Ku Kang and Chang-Soo Lee ................................................................................................ 130
P19: Fabrication of Flexible Organic Thermoelectric Generators by Inkjet Printing
Technique: Materials Screening and Assessment
Marco Cassinelli, M. Massetti and M. Caironi ..................................................................................... 131
P20: Different semiconducting behavior of PEDOT nanoparticles
Mario Culebras, José F. Serrano-Claumarchirant, Álvaro Seijas, Clara M. Gómez, Marta Carsí,
Maria J. Sanchis and Andrés Cantarero .............................................................................................. 132
P21: Hybrid films based on PEDOT and CNTs for thermoelectric applications
José F. Serrano-Claumarchirant, Mario Culebras, Rafael Muñoz-Espí, Marta Carsí, Maria J. Sanchis,Clara M. Gómez and Andrés Cantarero ............................................................................................... 133
P22: Towards the Fabrication of a Low Cost SnSe Thermoelectric Device
Matthew R. Burton, Tianjun Liu, Oliver Fenwick and Matthew J. Carnie .............................................. 134
P23: Fabric-Type Thermoelectric Generators using Carbon-Nanotube Yarns with Striped Doping
Takuya Koizumi, Yuki Sekimoto, Mitsuhiro Ito, Ryo Abe, Hirotaka Kojima, Takeshi Saito and
Masakazu Nakamura ........................................................................................................................... 135
P24: Seebeck measurements in PEDOT:PSS thin films
Ruiz-Cózar, G. Dalkiranis, A. F. Lopeandia, Ll. Abad ....................................................................... 136
P25: Effect of doping-induced charge localization on thermoelectric properties of
poly(nickel-ethylenetetrathiolate)
Yunpeng Liu, Dong Wang and Zhigang Shuai.................................................................................... 137
P26: Great enhancement of Photocatalytic and Photoelectrochemical Water Splitting Applications
of Bismuth Vanadate with Maximized Interfacial Coupling with RGO
Tayyebeh Soltani, Byeong-Kyu Lee .................................................................................................... 138
26
P27: Suppressing Thermal Transport in Chain-Oriented Conducting Polymers for
Enhanced Thermoelectric Efficiency
Dong Wang, Wen Shi, and Zhigang Shuai .......................................................................................... 139
P28: Non-Ideal Behavior in Organic Field-Effect Transistors Induced by Charge Trapping at
the Interface
Hio-Ieng Un, Jie-Yu Wang, and Jian Pei............................................................................................ 140
Special LecturesS1: Measurement System for Thermophysical Properties of Thin Films in a Broad
Temperature Range
H-W. Marx, V. Linseis......................................................................................................................... 145
S2: Thermoelectrics Based on Organic and Hybrid Materials
Stephen Shevlin and Olga Bubnova .................................................................................................... 146
P30: Heat-sink-free Flexible Organic Thermoelectric Generator Vertically Operating with
Chevron Structure
Daegun Kim, Duckhyun Ju and Kilwon Cho ....................................................................................... 142
P29: First-Principles Study on Thermoelectric Performance of Graphene/Ferroelectric PVDF Hybrid Organic Materials
Hikaru Horii, Yutaro Fujisaki, Masahiro Ito, Yoichiro Hasizume, Takashi Nakajima, Satoru Konabe, Takahiro Yamamoto............................................................................................................................. 141
PLENARY LECTURES
29
PL1: High Power Factor, Completely Organic Thermoelectric Nanocoatings for
Flexible Films and Textiles
Chungyeon Choa
, Choongho Yu a
, Jaime C. Grunlana,b,c
aDepartment of Mechanical Engineering, Texas A&M University, College Station, TX, USA bDepartment of Materials Sci. and Eng., Texas A&M University, College Station, TX, USA cDepartment of Chemistry,
Texas A&M University, College Station, TX, USA E-mail: [email protected]
In an effort to create a paintable/printable thermoelectric material, comprised exclusively of organic
components, polyaniline (PANi), graphene, and double-walled carbon nanotubes (DWNT) were alternately
deposited from aqueous solutions using the layer-by-layer assembly technique.[1]
Graphene and DWNT are
stabilized with an intrinsically conductive polymer, poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate)
(PEDOT:PSS). A 1 µm thick film, composed of 80 PANi/graphene-PEDOT:PSS/PANi/DWNT-PEDOT:PSS
quadlayers (QL) exhibits electrical conductivity (σ) of 1.88 x 105 S/m and a Seebeck coefficient (S) of 120
µV/K, producing a thermoelectric power factor (S2∙σ) of 2710 µW/(m∙K2). This is the highest value ever
reported for a completely organic material measured at room temperature. Furthermore, this performance
matches or exceeds that of commercial bismuth telluride. These outstanding properties are attributed to the
highly ordered structure in the multilayer assembly. The thermoelectric power output increased with the
number of cycles deposited, yielding 8.5 nW at 80 QL for ΔT = 5.6 K. A simple thermoelectric generator was
prepared with selectively-patterned, fabric-based system. The electric voltage generated by each TE device
increased in a linear relationship with both ΔT and the number of TE legs, producing ~ 5 mV with just five
legs and a ΔT of 9.7 K, as shown in Figure 1. By stabilizing, nanotubes and graphene with nitrogen-rich
molecules, n-type multilayer thin films with relatively high power factor have also been produced.[2]
This
unique TE coating system is water-based and uses only organic components. For the first time, there is a real
opportunity to harness waste heat from unconventional sources, such as body heat to power devices in an
environmentally-benign way.
Figure 1. Thermoelectric voltage generated by a cotton fabric-based device measured at an ambient temperature of
25.6 °C. With a ΔT of 9.7 K, this device generates 5.10 mV, corresponding to a Seebeck coefficient of 105 µV/K
[1] C. Cho, K. L. Wallace, P. Tzeng, J.-H. Hsu, C. Yu, J. C. Grunlan, Adv. Energy Mater., 2016, 6,
1502168.
[2] C. Cho, M. Culebras, K. L. Wallace, Y. Song, K. Holder, J.-H. Hsu, C. Yu, J. C. Grunlan, Nano Energy,
2016, 28, 426 - 432.
30
PL2: Thermoelectric Properties of Organic Polymers
Michael L. Chabinyc
Materials Department, University of California, Santa Barbara CA 93106-5050
E-mail: [email protected]
Organic semiconductors with a wide range of properties have been developed for flexible displays and
photovoltaics, but investigation of thermoelectric properties is relatively recent. Thermoelectric materials
are evaluated by the figure of merit ZT =S2T/ , that is determined by a combination of the Seebeck
coefficient, S, the electrical conductivity, σ, and the thermal conductivity, 𝜅. The limits of ZT in organic
materials is currently not understood. We have studied a large set of p- and n- type organic thermoelectric
materials and found strong correlation between the power factor and the electrical conductivity that is not
explained by conventional transport models. We find that changes in processing conditions can increase the
electrical conductivity by >50x at the same apparent carrier concentration in some polymers, while causing
smaller changes in the thermopower. The increase in performance can be understood by the nanoscale
connectivity between ordered domains and quantitated using synchrotron-based hard and soft X-ray
scattering methods. Studies of temperature-dependent electrical conductivity and thermopower in these
systems reveal critical insights into the density of states and transport mechanism in heavily doped
polymers. Prospects for the ultimate performance of polymer thermoelectrics will be discussed as well as
future challenges for materials design.
31
PL3: Organic Hybrid Thermoelectric Materials Involving Nanomaterials
Naoki Toshima
Tokyo University of Science Yamaguchi, Sanyo-Onoda, Yamaguchi 756-0884, Japan
E-mail: [email protected]
Thermoelectric technology has been developed using inorganic semiconducting materials. Recent global
issues on energy and environment require utilizing the thermoelectric technology for converting the waste heat
to electrical energy. The fact that most of the waste heat is generated at the temperatures below 150ºC has
suggested the organic thermoelectric materials to be of promise for energy conversion from the waste heat to
electricity.[1]
Many of the recent developments in the thermoelectrics have been promoted by the quantum
effect theoretically reported by Prof. M. S. Dresselhaus,[2]
which has resulted in preparation of various kinds of
the semiconducting nanomaterials. These semiconducting nanomaterials have found the organic polymers as
good counterparts, resulting in production of organic hybrid thermoelectric materials. Here, the organic hybrid
thermoelectric materials, involving the semiconducting nanomaterials, are presented mainly from our research
results.
The organic hybrid materials composed of conducting polyaniline and semiconducting bismuth telluride,
Bi2Te3, were prepared by physically mixing doped polyaniline in m-cresol and various sizes of Bi2Te3
particles.[3]
The nanometer-sized Bi2Te3 particles improved the Seebeck constant compared to that of the doped
polyaniline film, while the micrometer-sized ones did not. In the case of poly(3,4- ethenedioxythiophene)
poly(styrene sulfonate) (PEDOT-PSS) and Au nanoparticles, addition of a small amount of Au nanoparticles to
PEDOT-PSS improved the electrical conductivity and Seebeck coefficient,[4]
while addition of the larger
amount of Au nanoparticles or Au nanorods increased the electrical conductivity but decreased the Seebeck
coefficient.[5]
Carbon nanotubes (CNTs) having a high conductivity were found to form hybrid thermoelectric materials
with a high power factor.[6]
However, CNTs with a high conductivity are expensive. We found that the
conductivity of the less expensive CNTs with many defects, e.g., super-grown CNTs, can be improved by
doping with Pd nanoparticles.[7]
Nanoparticles of semiconducting polymer complexes, poly(nickel 1,1,2,2-
ethenetetrathiolate), (nPETT) were successfully prepared,[8]
which strongly interacted with CNTs forming a
good dispersions.[9]
Covering the nPETT/CNT hybrids with poly(vinyl chloride) produced stable and flexible
ternary films with a high thermoelectric performance.[10,11]
These results suggest that the strong interaction, which can be caused by significantly small
nanoparticles, is the important factors to achieve the hybrid materials with improved thermoelectric
performance.
[1] N. Toshima, Synth. Met., 2017, 225, 3-21.
[2] L. D. Hicks, M. S. Dresselhaus, Phys. Rev. B, 1993, 47, 12727-12731.
[3] N. Toshima, S. Ichikawa, J. Electr. Mater., 2015, 44, 384-390.
[4] N. Toshima, N. Jiravanichnun, J. Electr. Mater., 2013, 42, 1882-1887.
[5] A. Yoshida, N. Toshima, J. Electr. Mater., 2014, 43, 1492-1497.
[6] C. Cho, K. L. Wallace, P. Tzeng, J.-H. Hsu, C. Yu, J. C. Grunlan, Adv. Energy Mater., 2016, 6, 1502168.
[7] K. Oshima, J. Inoue, S. Sadakata, Y. Shiraishi, N. Toshima, J. Electr. Mater., 2017, 46, 3207-3214.
[8] K. Oshima, Y. Shiraishi, N. Toshima, Chem. Lett., 2015, 44, 1185-1187.
[9] K. Oshima, H. Asano, Y. Shiraishi, N. Toshima, Jpn. J. Appl. Phys., 2016, 55, 02BB07.
[10] N. Toshima, K. Oshima, H. Anno, T. Nishinaka, S. Ichikawa, A. Iwata, Y. Shiraishi, Adv. Mater., 2015,
27, 2246-2251.
[11] K. Oshima, S. Sadakata, H. Asano, Y. Shiraishi, N. Toshima, Mater., 2017, 10, 824.
32
INVITED LECTURES
35
I1: Increasing the Power Factor of PEDOT:PSS through Selective Blending of
Protic and Aprotic Ionic Liquids
Rachel A. Segalman
University of California, Santa Barbara
Ion conducting materials have previously been demonstrated to have very large Seebeck coefficients, and a
major advantage of polymers over inorganics is the high room temperature ionic conductivity. Notably,
poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid (PEDOT:PSS) demonstrates a significant but
short-term increase in Seebeck coefficient which is attributed to a large ionic Seebeck contribution. In this talk,
I will discuss how electrochemistry can be utilized to stabilize the Seebeck enhancement leading to stable
improvements to power factor in mixed conductor thermoelectrics. Ionic liquids (I.L.s) systematically modify
the relative populations of bipolarons and polarons in PEDOT:PSS and enhance its stable (long time plateau)
power factor by three orders of magnitude. By blending commercially-available PEDOT:PSS with known
concentrations of imidazole-based protic or aprotic ionic liquids (I.L.s), the Seebeck coefficient can be
selectively enhanced (protic cases) or suppressed (non-protic cases). The tailorable behavior of the Seebeck
coefficient is related to changes in the bipolaron/polaron population in the PEDOT:PSS blends depending on
the chemical nature of the I.L. The electrical conductivity also increases for all these systems and is
commensurate with PEDOT:PSS blendedwith other high boiling point solvents, leading to the large
enhancement in power factor. The protic I.L.s suppress the 𝜋-stacking of PEDOT domains and increase the
population of polarons, as probed through grazing incidence X-ray and UV-Vis-NIR spectroscopy
measurements. These findings indicate an efficient route to decouple chemical doping effects from
morphological changes and enhance the power factor of mixed organic thermoelectrics with possible future
incorporation of ion transport effects.
36
I2: Stable N-type Single Walled Carbon Nanotubes with New Organic Doping
Reagents for Future Thermoelectric Conversion
Tsuyoshi Kawai
Gradute School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara, 630-
0192, Japan
E-mail:[email protected]
Among various organic and carbon-based electronics materials, carbon-nanotubes (CNTs) are one of
the most attractive materials because of their stable and high electronic conductivity and high mechanical
strength. As like as all other carbon-based conductors, CNTs behaves as p-type material in which positive
charge carrier dominantly supports conducting current and thermoelectric voltages. There is intensive
demand for complementary p-type and n-type materials for various applications such as thermoelectric power
generations. We have studied and explored for various post chemical treatment on CNTs in a quest for stable
n-type CNTs and for reliable procedure to tune the doping level.
In this talk, I would like to summarize recent our results for stable n-type doping of CNTs concerning
molecular chemistry behind them.
[1] Y. Nonoguchi, M. Nakano, T. Murayama, H. Hagino, S. Hama, K. Miyazaki, R. Matsubara, M.
Nakamura and T. Kawai, Adv. Funct. Mater, 26, 3021 (2016).
[2] Y. Nonoguchi, A. Tani, T. Ikeda, C. Goto, N. Tanifuji, R. M. Uda, T. Kawai, Small, 13, 1603420
(2017)
[3] Y. Nonoguchi, S. Sudo, A. Tani, T. Murayama, Y. Nishiyama, R. M. Uda, T. Kawai, Chem.
Commun., 53, 10259 (2017)
37
I3: Large n- and p-type Thermoelectric Power Factors from Highly Enriched
Semiconducting Single-walled Carbon Nanotube Networks
Jeffrey Blackburn
In this presentation, I will discuss our efforts aimed at uncovering the fundamental thermoelectric
properties of semiconducting single-walled carbon nanotubes (s-SWCNTs), a unique class of one-dimensional
organic semiconductors with huge aspect ratios and large mobility values for both electrons and holes. The
theoretical Seebeck coefficients of s-SWCNTs are exceptionally high, in the range of several hundreds of
VK-1
to over 1 mVK-1
, and are much larger than the theoretical values of metallic SWCNTs. Furthermore,
the electrical conductivity of s-SWCNTs can be controlled by molecular charge transfer doping, and can reach
very large values (>1,000 Scm-1
). While these qualities emphasize the potential for s-SWCNT in
thermoelectric applications, as-synthesized SWCNT samples typically contain ~33% metallic SWCNTs and
the conductivity was often difficult to control precisely. Thus, for many years the thermoelectric power factors
of SWCNT samples remained low.
We have developed methods for extracting ultra-pure samples of s-SWCNTs with variable electronic band
gap distributions for the s-SWCNT population and undetectable metallic SWCNT impurities. These ultra-pure
s-SWCNT samples are dispersed in organic solvents, and can easily be fabricated into porous percolated s-
SWCNT networks, where the carrier density can subsequently be tuned with fine precision by the adsorption
of controlled amounts of redox dopants. The resulting s-SWCNT networks have thermoelectric power factors
that vary systematically with the carrier density injected by adsorbed redox dopants, with values that now
exceed 700 Wm-1K
-2 at the optimum doping level. Because the effective masses of electrons and holes are
roughly equivalent, these high power factors can be achieved for both n-type and p-type s-SWCNT networks.
We find the thermal conductivity to be heavily dominated by phonons. Interestingly, upon doping with redox
molecules the thermal conductivity decreases by a factor of 2 – 4 while the electrical conductivity increases by
several orders of magnitude. For two different s-SWCNT diameter distributions, we find peak zT values in the
range of zT ≈ 0.1.
We have uncovered a number of additional “extrinsic” considerations for the thermoelectric performance of
these highly enriched s-SWCNTs. First, removal of the polyfluorene polymer used to selectively extract s-
SWCNTs results in a universal improvement to the thermoelectric power factor, which can be correlated to an
improvement in charge carrier mobility. Second, we find that the thermoelectric power factor correlates
inversely with the average size of s-SWCNT bundles within the network. Finally, we demonstrate that a thin
(ca. 50 nm) alumina layer can be deposited onto s-SWCNT bundles by atomic layer deposition to stabilize the
thermoelectric performance of n-type s-SWCNT networks, which otherwise tend to degrade rapidly in air.
These considerations help to establish some design rules that should enable the fabrication of thermoelectric
generators comprised entirely of n-type and p-type s-SWCNT legs, where charge transport in both legs can be
easily balanced. These results help to establish the highly promising thermoelectric properties of controllably
doped s-SWCNT networks, suggesting that these materials are promising for thermoelectric applications either
on their own or as strategically utilized components of thermoelectric composites.
Bradley A. MacLeod, Noah J. Stanton, Isaac E. Gould, Devin Wesenberg, Rachelle Ihly, Zbyslaw R.
Owczarczyk, Katherine E. Hurst, Christopher S. Fewox, Christopher N. Folmar, Katherine Holman Hughes,
Barry L. Zink, Jeffrey L. Blackburn and Andrew J. Ferguson. Large n- and p-type thermoelectric power factors
from doped semiconducting single-walled carbon nanotube thin films. Energy & Environmental Science 2017,
10, 2168.
Norton-Baker, B., Ihly, R., Gould, I.E., Avery, A.D., Owczarczyk, Z., Ferguson, A.J., Blackburn, J.L.
Polymer-free Carbon Nanotube Thermoelectrics with Improved Charge Carrier Transport and Power Factor.
ACS Energy Letters, 2016, 1, 1212.
Avery, A.D., Zhou, B.H., Lee, J.H., Lee, E-S, Miller, E.M., Ihly, R., Wesenberg, D., Mistry, K.S., Guillot,
S.L., Zink, B.L., Kim, Y-H, Blackburn, J.L., Ferguson, A.J. Tailored Semiconducting Carbon Nanotube
Networks with Enhanced Thermoelectric Properties. Nature Energy, 2016, 1, 16033.
38
I4: Organic Metals: Potential Candidates for Thermoelectrics
Alexander Steeger1, Florian Huewe
1, Kalina Kostova
2, Laurence Burroughs
3, Irene Bauer
4, Peter Strohriegl
3,
Vladimir Dimitrov2, Simon Woodward
3 and Jens Pflaum1,6
1Julius-Maximilian University, Experimental Physics VI, Würzburg, Germany
2Bulgarian Academy of Sciences, Inst. of Org. Chemistry, Sofia, Bulgaria
3University of Nottingham, Carbon Neutral Lab. for Sustainable Chemistry, Nottingham, UK
4University of Bayreuth, Experimental Physics II, Bayreuth, Germany
5University of Bayreuth, Macromolecular Chemistry I, Bayreuth, Germany
6Center for Applied Energy Research (ZAE Bayern e.V.), Würzburg, Germany
E-mail: [email protected]
Polymeric semiconductors have been identified as a potential material class for thermoelectric applications
due to their low thermal conductivity κ and low-temperature, low-cost processibility.[1]
But due to their
inherent structural disorder, these compounds often lack an adequate electrical conductivity and thus, figure
merit zT = (σ S2/κ)T. Moreover, the need for sufficiently stable n- conductors challenges the realization of neat
polymer-based thermoelectric generators (TEGs).
Therefore, we have focused our temperature dependent thermoelectric investigations on crystalline organic
metals made up of radical ion salts and combining the advantage of low κ values with that of a good electrical
conductivity originating from the strong charge-transfer together with a spatially extended ordering along the
direction of transport.[2]
Choosing TTT2I3 and DCNQI2Cu as representatives, we were able to demonstrate p-
as well as n-type electrical conductivity with RT values of up to σ = 105 S/m, respectively. Furthermore, their
individual figures of merit show promising results, reaching zT ~ 0.15 at 40 K in DCNQI2Cu. First
prototypical all-organic TEGs based on TTT2I3 and DCNQI2Cu have been successfully operated (see figure)
and, without further optimization, have shown power outputs per active area of a few mW/cm2, thereby,
proving the class of radical ion salts to be of high interests for future thermoelectrics.[3]
Financial support by DFG (Project No. PF385/6) and EU-FP7 (H2ESOT, Project No. 308768) is gratefully
acknowledged.
a Sketch of an all-organic thermoelectric generator (TEG) based on DCNQI2Cu and TTT2I3 single crystals.b
Correspondig TEG power output characteristics and open-circuit voltage (inset) as function of temperature
difference.
[1] O. Bubnova et al., Nat. Mater., 2011, 10, 429.
[2] F. Huewe et al., Phys. Rev. B, 2015, 92, 155107.
[3] F. Huewe, et al., Adv. Mater., 2017, 29, 1605682.
39
I5: On the Manifestation of Electron-Electron Interactions in the Thermoelectric
Response of Semicrystalline Conjugated Polymers with Low Energetic Disorder
M. Statz1, D. Venkateshvaran
1, H. Sirringhaus
1 and R. Di Pietro
2
1University of Cambridge, Cavendish Laboratory, J. J. Thomson Avenue, CB3 0HE Cambridge, UK
2Hitachi Cambridge Laboratory, J. J. Thomson Avenue, CB3 0HE Cambridge, UK
E-mail: [email protected]
The recent development of amorphous and semicrystalline polymer semiconductors with low energetic disorder and saturation mobilities exceeding those of amorphous silicon has highlighted the limitations of a description of charge transport based on disorder, and requires us to rethink how charge carriers are transported
in these materials.[1, 2]
We study the charge carrier density and temperature dependence of electron mobility and Seebeck coefficient in the semicrystalline polymer P(NDI2OD-T2) with varying degrees of crystallinity using a thin-film-transistor structure. This architecture allows us to measure the two transport coefficients on the very same device, enabling us to characterize the type of transport and density of states of the material. While the different degree of crystallinity significantly impacts the charge carrier density dependence of the mobility, the Seebeck coefficient is temperature independent, follows Heikes' formula and has the same magnitude for different degrees of crystallinity. This result is not compatible with charge transport being limited by energetic disorder effects and is a direct evidence for narrow band conduction in semicrystalline polymer semiconductors. Furthermore, it envisions how tuning the crystallinity can be employed to selectively tune the transport coefficients and thereby significantly enhance the power factor for efficient thermoelectric generators.
We show that a consistent description of the measured transport coefficients in semicrystalline polymer
semiconductors requires the consideration of a spatially inhomogeneous and explicitly charge density
dependent density of states (Fig.1). We present a formalism considering electron-electron interactions as a
route to incorporate the physics of an explicitly charge density dependent density of states. This new
interpretation of charge transport has profound consequences on all aspects of polymer semiconductor
electronics and can lay the foundation of a further dramatic improvement in performance of this class of
materials.
Fig. 1: Seebeck coefficient versus conductivity as well as the fits with various transport models including the
approach that considers electron-electron interactions (CET)
[1] D. Venkateshvaran, M. Nikolka, A. Sadhanala, V. Lemaur, M. Zelazny, M. Kepa, M. Hurhangee, A. J.
Kronemeijer, V. Pecunia, I. Nasrallah, I. Romanov, K. Broch, I. McCulloch, D. Emin, Y. Olivier, J.
Cornil, D. Beljonne and H. Sirringhaus, Nature, 2014, 515, 384.
[2] R. Di Pietro, I. Nasrallah, J. Carpenter, E. Gann, L. S. Kölln, L. Thomsen, D. Venkateshvaran, K. O'Hara,
A. Sadhanala, M. Chabinyc, C. R. McNeill, A. Facchetti, H. Ade, H. Sirringhaus and D. Neher, Adv.
Funct. Mater., 2016, 26, 8011.
40
I6: Heat Harvesting Thermoelectric Textiles
Christian Müller
Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296
Göteborg, Sweden
E-mail: [email protected]
Recent advances in ubiquitous low-power electronics call for the development of light-weight and flexible
energy sources. The textile format is highly attractive for unobtrusive energy harvesting. In my talk, I will
present some of our recent work on thermoelectric textiles. I will discuss how n- and p-type yarns can be
prepared by coating silk from the silkworm Bombyx mori with carbon nanotubes or the conjugated
polymer:polyelectrolyte complex PEDOT:PSS. Some of these yarns feature a high degree of ambient stability
as well as the ability to withstand both machine washing and dry cleaning. Embroidery of base fabrics with such
conducting yarns readily permits the fabrication of thermoelectric modules.
41
I7: Morphology Control and Density of States Engineering Give Very High
Seebeck Coefficients in Organic Thermoelectric Blends
Guangzheng Zuo, Xianjie Liu, Mats Fahlman and and Martijn Kemerink
Department of Physics, Chemistry and Biology (IFM), Linköping University, Sweden
E-mail: [email protected]
We demonstrate a universal method to obtain record-high electronic Seebeck coefficients while
preserving reasonable conductivities in doped blends of organic semiconductors through rational design of the
density of states (DOS). A polymer semiconductor with a shallow HOMO level (P3HT) was mixed with
materials with a deeper HOMO (PTB7, TQ1) to form binary blends of the type P3HTx:B1-x (0 ≤ x ≤ 1) that
were p-type doped by F4TCNQ. For B = PTB7, we achieve a Seebeck coefficient S ~ 1100 µV/K at x =
0.10, while for B = TQ1 we find S ~ 2000 µV/K at x = 0.05. Surprisingly, we find that this methodology to
increase the Seebeck coefficient only works for strongly phase separated systems. In well-mixed systems
(P3HT:PTB7 with 5% DIO, P3HT:PCPDTBT), we find a much lower and more constant S, despite the energy
levels being (virtually) identical in both cases, see Figure.
The results are quantitatively interpreted in terms of a variable range hopping (VRH) model where a peak
in S (and a minimum in conductivity) arise when the percolation pathway contains both host and guest sites,
in which the latter acts as energetic trap. For well-mixed blends of the investigated compositions, VRH
enables percolation pathways that only involve isolated guest sites, whereas the large distance between
guest clusters in phase separated blends enforces (energetically unfavorable) hops via the host. The
experimentally observed trends are in good agreement with the results of kinetic Monte Carlo simulations
accounting for the differences in morphology.
The simulations are used to derive a design rule for parameter tuning. These results can become
relevant for low-power, low-cost applications like (providing power to) autonomous sensors, in which a high
Seebeck coefficient translates directly to a proportionally reduced number of legs in the
thermogenerator, and hence in reduced fabrication cost and complexity.
Left: Conductivity, Seebeck coefficient and power factor (PF) for P3HT:PTB7 dependent on active layer
composition. Dashed lines are without DIO (strong phase separation, see AFM image a); solid lines are with 5%
DIO (weak or no phase separation, see AFM image b). Note the presence (absence) of a peak in Seebeck
coefficient for morphology a (b). Both AFM images are for P3HT0.1:PTB70.9; all films are sequentially doped
by F4TCNQ.
42
I8: Computational design of thermoelectric polymers with large figure of merits
Zhigang Shuai, Dong Wang, Wen Shi, Yajing Sun
MOE Key Laboratory of Organic Opto-Electronics and Molecular Engineering, Department of
Chemistry, Tsinghua University, 100084 Beijing, China
We present our recent work in theoretical understanding and modeling of thermoelectric properties for
organic materials. Both electron-phonon scattering and carrier-impurities scattering have been taken
into consideration for the Boltzmann transport equation. The heat transport is modelled by first-
principles molecular dynamics compared with phonon Boltzmann equation considering the
anharmonic terms. We find that for polymeric materials, it is possible to realize phonon glass electron
crystal by engineering the crystallinity at the sub-micron scale by virtue of difference in the mean-free
path. We further investigate the electronic structure and thermoelectric power factors for the one-
dimensional organo-metallic coordinated polymers.
43
I9: Polymer-Dopant Synergies for Increased Hole and Electron Contributions
to Thermoelectric Power Factor
Howard E. Katz, Hui Li, and Xingang Zhao
Department of Materials Science and Engineering, Johns Hopkins University, 206 Maryland Hall,
3400 North Charles Street, Baltimore, MD, 21218, USA
E-mail: [email protected]
The power factor (PF) of thermoelectric materials, S2σ, where S is Seebeck coefficient and σ is
electrical conductivity, requires high charge density at an energy level ca. 0.1 eV below the transport
level, and high mobility of charge carriers in that level. Creating stable charge carriers in a
semiconducting polymer structure that maintains mobility is a materials chemistry challenge. This talk
will discuss two approaches to this challenge. For hole conductivity, we modified a standard thiophene
polymer structure (PQT12, Figure 1) with electron donating sulfur atoms between the dodecyl chains and
thiophene rings, and with ethylenedioxy substitution on half the thiophene rings, both of these
modifications intended to stabilize holes and achieve unusually high nonionic polymer conductivity. For
each of the modifications, one particular dopant yielded the highest σ and PF.[1]
For electron conductivity, we employed an emerging n-type polymer with enhanced electron accepting properties and an air-stable ionic dopant to achieve the first step toward air stability of electron σ
and PF.[2]
One notable aspect of both of these investigations are that the correlations of S and σ are
consistent with predictions of recently published models. These correlations validate the internal consistency
of both of the parameter measurements and the placement of Fermi and transport energies in relative
positions similar to what is found in other reported thermoelectric polymers while achieving relatively high
mobility in the doped forms. A second aspect is the constancy of S over the minutes time scale following
imposition of a temperature difference, decreasing the likelihood of a major ionic contribution to S. Spectroscopic measurements were used as alternate means of observing charge carriers, transistor data
provided estimations of mobility, and x-ray scattering revealed the effects of doping on polymer chain
packing.
Figure 1. Structures of semiconducting polymers used in this study
[1] H. Li, M.E. DeCoster, R.M. Ireland, J.; Song, P.E. Hopkins, H.E. Katz, J. Am Chem. Soc. 2017, 139,
11149-11157.
[2] X. Zhao, D. Madan, Y. Cheng, J. Zhou, H. Li, S.M. Thon, A.E. Bragg, M.E. DeCoster, P.E.; Hopkins, H.E.;
Katz, Adv. Mater. 2017, 29, 1606928
44
I10: Electric Field Modulations Assisted Development of High Performance n-type
Organic Thermoelectric Materials
Chong-an Di, Ye Zou, Daoben Zhu
Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
E-mail: [email protected], [email protected]
Organic semiconductors are considered as attractive thermoelectric candidates owing to their intrinsically
low thermal conductivity, excellent flexibility, and solution processability.[1]
Benefiting from rapid development of materials sciences and chemical doping engineering, organic thermoelectrics (TEs) have made great achievements, indicated by the dramatically improved figure of merit (ZT) and development of various
functional devices.[1-3]
In this presentation, we will demonstrate our recent field-modulated TE studies on high
mobility organic semiconductors.[4-6]
The systematic studies allow effective screening of promising TE materials based on organic semiconductors. Notably, the combination of electric field modulation with fine-
tuned chemical doping enabled successful development of two kinds of novel n-type TE materials.[5,6]
As an example, the chemically doped A-DCV-DPPTT, a small molecule with aromatic structure, exhibits an
electrical conductivity of 5.3 S cm−1
, a high power factor (PF373 K) up to 236 μW m−1
K−2
, and maximum ZT
over 0.2.[6]
The performance is the highest value reported to date for thermoelectric materials based on organic small molecules. These results demonstrate that high mobility organic semiconductors are promising candidates for high performance OTE materials and the electric field modulation can accelerate the search for promising candidates. In addition to these results, perspectives on organic TE devices are also involved in the presentation.
[1] C. A. Di, W. Xu, D. B. Zhu, Natl. Sci. Rev., 2016, 3, 269-271.
[2] F. J. Zhang, Y. P. Zang, D. Z. Huang, C. A. Di, D. B. Zhu, Nat. Commun., 2015, 6, 8356.
[3] D. Z. Huang, Y. Zou, F. Jiao, F. J. Zhang, Y. P. Zang, C. A. Di, W. Xu, D. B. Zhu, ACS Appl. Mater.
Interfaces, 2015, 7, 8968−8973.
[4] F. J. Zhang, Y. P. Zang, D. Z. Huang, C. A. Di, X. K. Gao, D. B. Zhu, Adv. Funct. Mater., 2015,
25, 3004-3012.
[5] D. Z. Huang, C. Wang, Y. Zou, X. X. Shen, Y. P. Zang, H. G. Shen, X. K. Gao, Y. P. Yi, W. Xu, C. A. Di,
D. B. Zhu, Angew. Chem. Int. Ed., 2016, 55 , 10672-10675.
[6] D. Z. Huang, H. Y. Yao, Y. T. Cui, Y. Zou, F. J. Zhang, C. Wang, H. G. Shen, W. L. Jin, J. Zhu, Y. Diao, W.
Xu, C. A. Di, D. B. Zhu, J. Am. Chem. Soc., 2017, 139 , 13013-13023.
45
I11: N-doped conducting polymers for thermoelectrics
Simone Fabiano
1Laboratory of Organic Electronics, Department of Science and Technology, Linköping University,
Norrköping SE-60174, Sweden
E-mail: [email protected]
Conducting polymers are emerging as potential thermoelectric materials for low temperature range
applications (< 200 °C), without the need of expensive, or even toxic metal-based compounds. However,
building efficient thermoelectric devices requires high-performance complementary p-type (hole-
transporting) and n-type (electron-transporting) materials. Up to date, all-organic thermoelectric devices
have been difficult to manufacture due to the limitations encountered by the n-type organic
semiconductors. Unlike their p-type counterparts, n-doped conducting polymers typically suffer from a
low electrical conductivity (< 0.01 S/cm). Despite continuous efforts to understand charge transport
mechanism in these materials and how it affects the device performance, the interplay between chemical
structure, polaron delocalization length, and conductivity remains unclear. Here we show that n-doped
polymers do not necessarily have to follow the typical design rules of semiconducting polymers for
field-effect transistors. In contrast to undoped polymers where in fact regioregularity of the backbone and
crystallinity are pursued for their beneficial effect on charge carrier mobility, polymers used in their doped
state should be designed to have long polaron delocalization lengths in order to reach high conductivity.
In particular, we will show that linear torsion-free polymer backbones enable a delocalized anion to
form upon doping, leading to high conductivity and power factor as compared to distorted n-doped
polymers. Understanding these principles will guide the design of next-generation high-conductivity
polymers for thermoelectric applications.[1]
[1] S. Wang, H. Sun, U. Ail, M. Vagin, P. O. Å Persson, J. W. Andreasen, W. Thiel, M. Berggren, X.
Crispin, D. Fazzi, S. Fabiano, Adv. Mater. 2016, 28, 10764–10771
46
I12: Simultaneous determination of the thermal conductivity and thermal
boundary resistance in supported thin organic films
Xabier Rodríguez-Martínez, Osnat Zapata Arteaga, Aleksandr Perevedentsev, Alejandro R. Goñi, Sebastian
Reparaz, Mariano Campoy Quiles
Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193
Bellaterra, Spain
E-mail: [email protected]
The development of organic and hybrid thermoelectric materials has thus far focused on the electronic
part (Seebeck and electrical conductivity). However, knowledge of the thermal conductivity is also crucial
in order to determine the thermoelectric figure of merit and the materials efficiency. The lack of thermal
conductivity data is due to the combination of two factors. On the one hand, the standard techniques to
obtain thermal conductivity of thin films, such as 3w, are time consuming and require elaborated
processing steps often not compatible with solution processed thin (and often rough/porous) organic films.
On the other hand, polymeric or carbon nanotube samples can exhibit strong anisotropy in the thermal
properties, which complicates its measurement further.
In this contribution, we show the use of Raman scattering as a tool to determine the thermal conductivity
of supported thin films.[1]
In this technique, the laser used to measure the Raman signal is also used to heat
the sample. The amount of absorbed heat can be easily tuned by varying the film thickness. First, we
will present the quantification of the Raman signal as a function of the film properties.[2]
Then, Multiphysics
modelling is used to couple the Maxwell equations (that describe laser light absorption) and the Fourier
heat diffusion equations. Fitting of the experimental data allows for determining the thermal conductivity
of the thin film. Moreover, the thermal boundary resistance between the film and the substrate is also
determined. This parameter is of paramount relevance for real life applications, as has been shown by
the Milan´s group.[3]
We apply this method to different organic semiconductors, including P3HT,
PCDTBT and PCBM,[4]
and compare our results to standard measurements using 3w. Interestingly, this
method might be extended to investigate anisotropic as well as inhomogeneous samples.
[1] J. S. Reparaz et al Rev. Sci. Instrum. 2014, 85, 034901.
[2] X. Rodríguez-Martínez et al J. Mater. Chem. C. 2017, 5, 7270-7282.
[3] D. Beretta et al, Sustainable Energy Fuels, 2017,1, 174-190.
[4] X. Rodríguez-Martínez, A. R. Goñi, S. Reparaz, M. Campoy Quiles, In preparation. 2017.
47
I13: Promising Polymeric Thermoelectric Thin Films of Poly(Ni-
ethylenetetrathiolate) and Polythiophene Prepared by Electrochemical deposition
Wei Xu, Yimeng Sun, Chong-an Di, Daoben Zhu
Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
E-mail: [email protected], [email protected]
Tuning structural ordering and doping level is the general strategies for optimizing the TE performance of
conducting polymers. Alkyl chain substitutions are essential for -conjugated molecular materials to
achieve efficient electrical transport properties and solution processability. However, insulating saturated
alkyl chains do not contribute to the charge transport directly, and the increased crystallinity of polymers will
lead to higher lattice thermal conductivity. For polymers with the same conjugated backbone, higher carrier
concentration could be obtained for the polymer without side alky chain under the same doping level, which
may lead to higher power factor if the charge carrier mobility less sensitive with the side chain
substitutions. This consideration has inspired us to explore TE properties of unsubstituted conjugated
polymers prepared by electrochemical polymerization, an alternate low-cost wet chemical approach for the
preparation of large area thin films.
Poly(nickel ethenetetrathiolate) (poly(Ni-ett)) is a one dimensional ladder-type polymer, which can be
deposited on different substrates through a electrochemical process. We find that these thin films display
promising thermoelectric properties with high electrical conductivity, seebeck coefficient and low thermal
conductivity. The figure of merit (ZT) of these films can reach up to 0.3 under room temperature, which is
the highest ZT value ever reported for n-type organic materials.[1]
Furthermore, poly[Kx(Ni-ett)] film is
patterned via an electrochemical process on a prepatterned PET substrate with printed PDMS layer serving as a
mask. A unipolar TE device can be fabricated with these patterns.[2]
The highly regular polythiophene film prepared in boron fluoride ethylether could display an
electrical conductivity reaching up to 700Scm-1
. By adjusting the current density for deposition,
optimized ZT value of 0.1 under room temperature could be achieved with the sample with electrical
conductivity, seebeck coefficient and thermal conductivity of 459 Scm-1
, 42.7V K-1
and 0.247Wm- 1
K-1
,
respectively.
[1] Y. Sun, L. Qiu, L. Tang, H. Geng, H. Wang, F. Zhang, D. Huang, W. Xu, P. Yue, Y. Guan, F. Jiao,
Y. Sun, D. Tang, C. Di, Y. Yi, D. Zhu, Adv. Mater., 2016, 28 (17), 3351-3358.
[2] L. Liu, Y. Sun, W. Li, J. Zhang, X. Huang, Z. Chen, Y. Sun, C. Di, W. Xu and D. Zhu, Mater. Chem.
Front., 2017, 1, 2111-2116.
48
I14: Fabrication of highly oriented and crystalline conducting polymer films
with anisotropic charge transport and thermoelectric properties
Martin Brinkmann1, Amer Hamidi-Sakr
1, Vishnu Vijayakumar
1, Laure Biniek
1, Patrick Lévêque
2, Jean-Louis
Bantignies3, David Maurin
3, Nicolas Lecler
4
1Université de Strasbourg, CNRS, ICS UPR22, F67000 Strasbourg, France 2Université de Strasbourg, CNRS, ENGEES, INSA, ICube UMR 7357, F-67000 Strasbourg, France
3Université de Montpellier, Laboratoire Charles Coulomb, F34095 Montpellier,
France 4Université de Strasbourg, CNRS, ICPEES, UMR 7515, F67000 Strasbourg, France
E-mail: [email protected]
A general method is proposed to produce oriented and highly crystalline conducting polymer layers by
combining the controlled orientation/crystallization of polymer films by high-temperature rubbing with a
soft-doping method based on spin-coating a solution of dopants in an orthogonal solvent. Doping highly
aligned films of regioregular poly(3-alkylthiophene)s and poly(2,5-bis(3- dodecylthiophen-2-yl) thieno [3,2-
b] thiophene) (PBTTT) with 2,3,5,6-tetrafluoro-7,7,8,8- tetracyanoquinodimethane (F4TCNQ) yields highly
oriented conducting polymer films. These doped layers display highly polarized UV-Visible-NIR
absorption, anisotropy in charge transport and thermoelectric properties. Transmission Electron
Microscopy and polarized UV-Vis-NIR spectroscopy help understand and clarify the structure of the films
and the doping mechanism. Interestingly, F4TCNQ- anions are incorporated into the layers of side chains
and orient with their long molecular axis perpendicular to the polymer chains. However, the ordering of
dopant molecules in the layers of alkyl side chains depends closely on the length and packing
(interdigitated/non- interdigitated) of the alkyl side chains. Increasing the dopant concentration results in a
continuous variation of unit cell parameters of the doped phase and there is no evidence for coexistence of
doped and undoped P3HT crystals in thin films. Evidence is also found that amorphous domains are
marginaly doped by F4TCNQ. The high orientation results in anisotropic charge conductivity () and
thermoelectric properties that are both enhanced in the direction of the polymer chains (=22±5 S/cm and
S=60±2 µV/K). The method of fabrication of such highly oriented conducting polymer films is versatile
and is applicable to a large palette of semi-conducting polymers such as the family of PBTTTs.
[1] A. Hamidi Sakr et al., Adv. Funct. Mat. 2016, 26, 408.
[2] A. Hamidi-Sakr, et al, Adv. Funct. Mat. 2017, 27, 1700173
49
I15: Metal Coordinated Polymer Thermoelectrics and Devices
Shannon Yee1
1 G. W. W, School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
Within the last 3 years, thermoelectric technologies have seen renewed global deployment providing unique
solutions to pressing thermal problems. Today thermoelectric technologies are helping to ensure vaccines
viably reach the most remote locations in the world, are providing personal comfort in wearable devices
addressing medical circulatory conditions, and are being designed for integration into electric vehicles thereby
reducing the global warming contributions of refrigerants in conventional air conditioning systems. The
majority of these technologies have resulted from innovative engineers utilizing conventional materials in
niche applications, however, additional societal contributions can be achieved by leveraging the large-area
processability and abundance of polymer-based thermoelectrics.
Unfortunately, the material performance of polymer-based thermoelectric materials is lacking compared to
their inorganic counterparts. To circumvent this challenge, composites or hybrid organic-inorganic materials
are often employed in functional devices. Furthermore, while there is an abundance of p-type materials to
select from, there are few air-stable n-type thermoelectric materials. Metal coordinated polymers (or metallo-
organic polymers) are one promising class of thermoelectric materials where a metal (or semimetal) atom is
present along the polymer backbone. This structure produces periodic centers of high electron density, which,
when coupled to the vibrational modes (e.g., vibrons or phonons), could result in appreciable power factors.
Both air-stable p-type and n-type metal coordinated polymers can be readily synthesized from abundant
materials and are promising scalable alternatives to inorganics that leverage solution processing.
This talk will first provide a motivating overview of emerging thermoelectric technologies being developed
through the Scalable Thermal Energy Engineering Laboratory (STEEL) directed by Prof. Shannon Yee at the
Georgia Institute of Technology. Next, this talk will discuss progress in synthesizing and controlling the
thermoelectric properties of poly(nickel-ethenetetrathiolate) (i.e., Ni-ETT) and poly(nickel-tetrathiooxalate)
(i.e., Ni-TTO), which are both air-stable n-type thermoelectric materials containing nickel along the polymer
backbone. Next, this talk will discuss recent on-going work studying p-type chalcogenophene polymers,
where the isovalent series of polythiophene through polytellurophene will be discussed. Finally, this talk will
introduce new thermoelectric device architectures, specifically printable and knittable devices, that are enabled
by these materials. Throughout this talk emphasis will be placed on the engineering and scaling challenges,
which have been overlooked in the pursuit of high performance materials, but are most critical to realizing
thermoelectric devices.
50
I16: Direct Observation of Peltier Cooling in Molecular Junctions
Longji Cui1, Ruijiao Miao
1, Kun Wang
1, Dakotah Thompson
1, Linda A. Zotti
2, Juan Carlos Cuevas
2,3*, Edgar
Meyhofer1*
, Pramod Reddy1,4
1Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
2Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC),
Universidad Autónoma de Madrid, Madrid, 28049, Spain 3Department of Physics, University of Konstanz, 78457 Konstanz, Germany
44Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109, USA
Email: [email protected]
The study of thermoelectricity in molecular junctions is of fundamental interest and important for
future development of a variety of technologies including cooling (refrigeration) and heat-to- electricity
conversion. Recent experimental progress in probing the thermopower (Seebeck effect) of molecular
junctions has enabled a deeper understanding of the relationship between thermoelectricity and molecular
structure. Here we report first observations of Peltier cooling in molecular junctions, which had so far been
inaccessible due to experimental challenges. We studied Au-Biphenyl-4,4- dithiol-Au, Au-Terphenyl-4,4-
dithiol-Au, and Au-4,4-Bipyridine-Au junctions and revealed the relationship between heating or cooling and
charge transmission characteristics [1]
. We show how our detailed state-of-the-art calculations support the
experimental conclusions.
Schematic description of the origin of the Peltier effect in a molecular junction where transport is dominated by
the HOMO (left) and example of geometries used to compute the transport properties.
[1] L. Cui, R. Miao, K. Wang, D. Thompson, L. A. Zotti, J. C. Cuevas, E. Meyhofer, P. Reddy, Nat.
Nanotechnol., accepted.
51
I17: Quantum Thermopower in Molecular Junctions
Nicolás Agrait
Dept. Condensed Matter Physics and Condensed Matter Physics Center (IFIMAC),
Universidad Autónoma de Madrid, SPAIN and IMDEA Nanoscience, SPAIN
E-mail: [email protected]
Molecular junctions are promising candidates to achieve high thermoelectric efficiencies due to the
discreteness of the energy levels responsible for transport and the tunability of their properties via chemical
synthesis, electro-static gates, or pressure. After a general introduction to thermoelectric effects in the
nanoscale, I will present our recent results on the thermoelectric properties of fullerenes. Using a modified
scanning tunneling microscope (STM), we find that in contrast with C60 [1] the endohedral fullerene Sc3N@C80
[2] forms junctions in which the magnitude and sign of the thermopower depend strongly on the orientation of
the molecule and on applied pressure. We demonstrate that the origin of this exceptional behavior is the
presence of a sharp resonance near the Fermi level created by the Sc3N inside the fullerene cage, whose
energetic location, and hence the ther- mopower, can be tuned by applying pressure. These results reveal that
Sc3N@C80 is a bi-thermoelectric material, exhibiting both positive and negative thermopower, and provide an
unambiguous demonstration of the importance of transport resonances in thermoelectric performance of
organic materials.
Figure 1. Pressure variation of endohedral fullerene Sc3N@C80.
[1] C. Evangeli, K. Gillemot, E. Leary, M.T. Gonzalez, G. Rubio-Bollinger, C.J. Lambert, and N. Agraït,
Engineering the Thermopower of C60 Molecular Junctions, Nano Letters 13, 2141 (2013).
[2] L. Rincón-García, A.K. Ismael, C. Evangeli, I. Grace, G. Rubio-Bollinger, K. Porfyrakis, N. Agraït, and
C.J. Lambert, Molecular design and control of fullerene-based bi-thermoelectric materials, Nature Mater.
15, 289-293 (2016)
ORAL CONTRIBUTIONS
55
A1: Nanostructured organic thermoelectrics-PEDOT nanowires for printed
devices
Verena Schendel, Silas Aslan, André Gall, Andrés Roesch, Matthias Hecht, Frederick Lessman and Uli
Lemmer
Karlsruhe Institute of Technology, Light Technology Institute, Engesserstrasse 13, 76131 Karlsruhe
E-mail: [email protected]
Organic semiconductors have been successfully utilised for organic electronic devices ranging from
photovoltaics to flexible OLED displays. However, the field of thermoelectrics - materials that convert a
temperature difference into electrical energy- has been dominated over the last decades by inorganics, which
are mainly based on low abundant and toxic compounds such as Bi2Te3. This has been mostly attributed to the poor figure of merit (ZT) of organics in comparison to their inorganic counterparts and has been seen by the
community as the show-stopper for their ultimate use.
Over the past decade, new material designs and synthetic strategies have boosted ZT substantially and by
these means have resurrected interest in organic thermoelectrics and devices. In particular, nanostructuring of
thermoelectric materials offer one promising route to enhance ZT significantly. Here, we show the enhanced
thermoelectric properties of PEDOT nanowires in comparison to their bulk counterparts and demonstrate – for the first time- their successful integration in printed thermoelectric generators.
56
A2: Thermoelectric Polymer Aerogels for Pressure–Temperature Sensing
Applications
Shaobo Han, Fei Jiao, Zia Ullah Khan, Jesper Edberg, Simone Fabiano, and Xavier Crispin
Department of Science and Technology, Linköping University, S-60174 Norrköping, Sweden
E-mail: [email protected]
The authors, in this study, convey properties of thermoelectric and semimetallic of PEDOT:PSS into a
three-dimensional material which is a unique combination of nanocellulose and conducting polymers, to
create thermoelectric polymer aerogels. These aerogels originally give confused signals when they are used
as pressure and temperature dual parameter sensors. [1] However, with a simple chemical vapor treatment,
these aerogels are in fact exceptional dual parameter pressure and temperature sensors, in which the
reading of pressure and temperature occurs with a single material and without cross-talking of the two
parameters. This optimization is inspired from the authors' experience in thermoelectric materials for which it
is important to manipulate the charge transport regime. The decoupling between the pressure and temperature
readings obtained by the chemical vapor treatment was enabled by an electronic transport close to
semimetallic.[2] Note that this chemical vapor treatment also increased the pressure sensitivity of the
aerogel by three order of magnitude. Finally, since the aerogel is flexible and elastic, the findings of this
study are likely to have important implications in technologies interfacing with robot or even human body,
as in the field of electronic-skin.
Fig. 1, Thermoelectric polymer aerogel based on PEDOT:PSS and nanofibrillated cellulose .
[1] Z. U. Khan, J. Edberg, M. M. Hamedi, R. Gabrielsson, H. Granberg, L. Wagberg, I. Engquist, M.
Berggren, X. Crispin., Adv. Mat., 2016, 28, 4556-4562.
[2] S. Han, F. Jiao, Z. U. Khan, J. Edberg, S. Fabiano, X. Crispin., Adv. Fun. Mat., 2017, 03549.
57
A3: Printed Flexible Thermoelectric Device of the Organic/Inorganic composite
Koji Miyazaki1, Tomohide Yabuki
1, Laurent Tranchant
1, and Kunihisa Kato
2
1Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu, JAPAN 2Lintec Co. Ltd., 7-7-3 Tsuji, Minami-ku, Saitama, JAPAN
E-mail: [email protected]
We have developed a thermoelectric device by using a printing method. A mixture of Bismuth Telluride
micro-particles and PEDOT:PSS as a conductive polymer with several organic additives was prepared. The
poly-acrylic acid is added in the mixture for connecting bismuth telluride particles mechanically and
electrically. The measured figure of merit of the bismuth telluride thin film fabricated by spin-coating the
mixture was 0.2 at 300K due to its low thermal conductivity [1]
. The measured thermal conductivity was
much lower than the predicted value by a conventional model for the thermal conductivity of a composite.
We investigated the low thermal conductivity of the composite by measuring the interfacial resistance
between the organic material and the inorganic material. The Bismuth Telluride films were deposited on
the alumina substrate by arc-plasma method, and the Poly-imide films were made by spin-coating of
poly-amic acid and annealing at 473K. The cross-plane thermal conductivity was measured by a
differential 3 omega method. The measured thermal resistance was the order of 10-7
(m2･K)/W. It was
about 10 times higher than the interfacial resistance between inorganic-inorganic materials, but it is
similar to the interfacial resistance between organic-inorganic materials. The thermal conductivity of the
composite film of organic and inorganic materials was well explained by the high thermal resistances.
Now, we have developed the organic materials for the mixture to print them to make a thermoelectric
device as shown in Fig. 1. The thermal design is also important to enhance the output power of
thermoelectric device as well as the development of the materials with high-ZT [2]
. The power density
of the device was 35[W/c m2] at 323K, and the total output power becomes 1mW.
Figure 1. Developed printed thermoelectric generator
[1] K. Kato, H. Hagino, and K. Miyazaki, J.Electronic. Mater., 2013, 42, 1313-1318.
[2] S. Hama, T. Yabuki, L.Tranchant, and K. Miyazaki, J. Phys.: Conf. Series, 2015, 660, 012088 .
58
A4: PEDOT-PSS electrodes for Thermogalvanic Cells
Kosala Wijeratne, Ujwala Ail, Robert Brooke, Mikhail Vagin, Xavier Crispin
Laboratory of Organic Electronics, Department of Science and Technology, Campus Norrköping
Linköping University, S-60174 Norrkoping, Sweden
E-mail: [email protected]
Converting waste heat into electricity has become more important than ever due to the growing energy
demand and environmental issues accompanied with the use of fossil energy. A promising way to convert
waste heat directly into electricity is by using thermoelectric generators (TEGs). Standard TEGs are based on
inorganic semiconductors and the challenge is to find low-cost and abundant thermoelectric materials. An
alternative emerging technology to thermoelectric generators is a thermoglavanic cell (TGCs). A
thermoglavanic cell is an electrochemical device which allows direct conversion of thermal energy to electrical
energy. It consists of an electrolyte with redox couple and two identical electrodes set at different
temperatures. The most studied thermoglavanic cell is made of an electrolyte containing aqueous 0.4 M
ferri/ferrocyanide redox couple with platinum electrodes. In this system, the temperature difference creates a
difference in the redox potential of the ferri/ferrocyanide electrolyte at the platinum electrodes allowing to
generate power. The drawback is that noble Pt electrodes are expensive.
Conducting polymer is one of the promising candidate electrode for thermoglavanic cells because it does
not oxidize like most of the metals and reaches decent electrical conductivity (1000 S/cm). Furthermore,
conducting polymers can be synthesized at low temperature from solution processing and it is composed of
atomic elements of high abundancy. Poly(3,4-ethylenedioxythiophene)- poly(styrenesulfonate) (PEDOT-PSS)
is chosen as the conducting polymer electrode. It is known to transport both electronic and ionic charge
carriers. It conductivity can be tuned by the addition of polar solvents such as dimethyl sulfonate (DMSO). We
study the effect of DMSO on the electron transfer to the ferri/ferrocyanide electrolyte. We characterize TGCs
with PEDOT-PSS electrode and investigate the impact of the conductivity of the polymer electron on the
performance of the TGCs.
59
A5: An apparatus for accurate measurements of thermal conductivity
Ekaterina Selezneva1,2
, Pablo Díaz-Chao2, Andres Muniz-Piniella
2, Alexandre Cuenat
2, Henning Sirringhaus
1
1 Cavendish Laboratory, University of Cambridge, 19 J J Thomson Avenue, Cambridge CB3 0HE, UK
2 National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK
E-mail: [email protected]
We present an apparatus for thermal conductivity measurements based on the comparative longitudinal heat
flow method (ASTM-E1225, ASTM-D5470). From all thermoelectric transport coefficients, thermal
conductivity is the one most challenging to measure due to the difficulties associated with removal of parasitic
heat conduction passes. Significant knowledge of the phenomena and experimental efforts are thus required to
keep measurement uncertainty below acceptable limits. Although the apparatus is primarily aimed to measure
thermal conductivity of bulk and interface materials, we also demonstrate its ability to measure directly the
figure of merit of thermoelectric modules, which is especially relevant in view of potential industrial
applications.
60
A6: Thermal conductivity in layer-engineered inorganic-organic thin films
Fabian Krahl1, Ashutosh Giri
2, John P. Tomko
2, Tommi Tynell
1, John P. Hopkins
2, Maarit Karppinen
1
1Aalto University, Department of Chemistry and Materials Science, Fi-00076 Aalto, Finland 2University of Virginia, Department of Mechanical Engineering, Charlottesville, VA 22904-4746,
USA
E-mail: [email protected]
Reducing the thermal conductivity while not affecting the electrical conductivity is a key step towards
increasing the efficiency of thermoelectric materials. One such approach is to fabricate superlattices.[1]
In
particular, layered inorganic-organic hybrid superlattice thin films are interesting as they combine mutually
very different constituents. In our group we utilize the emerging Atomic/Molecular Layer Deposition
(ALD/MLD) technique to fabricate such state-of-the-art thin-film structures. The self- limiting growth process
of ALD/MLD allows an unprecedented control in layer engineering with a slow but highly controlled growth
rate.
We have already shown a decrease by an order of magnitude in thermal conductivity in the hybrid
ZnO/benzene and TiO2/benzene superlattice thin films compared to plain ZnO and TiO2 films, respectively.[2–4]
This decrease originates most likely from scattering of the phonons at the inorganic- organic interfaces.[2,5]
In
the present work we introduced a gradient in the material. Instead of an evenly spaced superlattice we engineer
a continuously decreasing or increasing spacing between the benzene sublayers (see Figure 1a). The gradient
materials are compared to previously reported superlattices of the same material system. We find that gradients
can match superlattices and possible even surpass them in terms of lowering the thermal conductivity (see
Figure 1b). Our research extends the data for engineered thin films to gradient layered systems that has, to our
knowledge, not been provided before.
Figure 1 (a) Simplyfied idea of phonons scattered in gradients, superlattices and plain ZnO . (b) Thermal
conductivity of several thin film design plotted against the average ZnO sub-block thickness in the films.
[1] L. D. Hicks, M. S. Dresselhaus, Phys. Rev. B 1993, 47, 12727.
[2] A. Giri, J.-P. Niemelä, T. Tynell, J. T. Gaskins, B. F. Donovan, M. Karppinen, P. E. Hopkins, Phys. Rev. B
2016, 93, 115310.
[3] T. Tynell, A. Giri, J. Gaskins, P. E. Hopkins, P. Mele, K. Miyazaki, M. Karppinen, J. Mater. Chem. A
2014, 2, 12150.
[4] J.-P. Niemelä, A. Giri, P. E. Hopkins, M. Karppinen, J. Mater. Chem. A 2015, 3, 11527.
[5] A. J. Karttunen, T. Tynell, M. Karppinen, Nano Energy 2016, 22, 338.
61
A7: Morphological tuning of thermal conductivity in halide perovskite thin films
Tianjun Liu1,2
, Thibault Degousée1,2
, Sinclair Ryley Ratnasingham3, Pritesh Ravji Varsani
1, Joe Briscoe
1,
Martyn McLachlan3, and Oliver Fenwick.
1,2
1School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom.
2The Organic Thermoelectrics Laboratory, Materials Research Institute, Queen Mary University of London Mile End Road, London E1 4NS, United Kingdom.
3 Department of Materials and London Centre for Nanotechnology, Imperial College London, London SW7 2AZ, United Kingdom.
E-mail: [email protected]
The halide perovskites have recently attracted interest for thermoelectric applications due to their
intrinsically low thermal conductivity[1,2] combined with high charge carrier mobilities. Since the intrinsic
thermal conductivity of these materials is so low, it is worth considering how much further it can be reduced
by nanostructuring. In this study we use in-plane measurements to study the effect of grain size and
deposition method on the thermal conductivity. We find the thermal conductivity to be highly tunable down to
~0.20 W/mK.
We first study films of methylammonium lead iodide (MAPbI3) of various thicknesses formed by thermal
co-evaporation of methyl ammonium iodide with PbCl2. We measure in-plane thermal conductivities and find
that for 100 nm thick films they are quite similar to bulk values found in the literature. As the film
thickness is reduced, average grain size is also reduced and we observe the emergence of PbI2 inclusions.
Accordingly, the thermal conductivity decreases with film thickness.
However, we also explore other deposition techniques of MAPbI3 films which give larger grain sizes, but
rather counterintuitively result lower thermal conductivities. These methods includes aerosol- assisted
chemical vapour deposition (AACVD) which yields several micron thick films and grain sizes similar to the
film thickness. The thermal conductivity of these films can are ~0.20 W/mK at room temperature and ~0.32
W/mK at 100K.
Figure – Thermal conductivity of thermally evaporated films of MAPbI3 as a function of temperature and thickness.
[1] W. Lee et al., PNAS 114 (33), 8693-8697 (2017).
[2] Z. Guo et al., J. Phys. Chem. C 120, 6394−6401 (2016).
62
A8: Ionic Thermoelectric Paper
Fei Jiao1, Ali Naderi
2, Dan Zhao
1, Joshua Schlueter
3, Maryam Shahi
3, Jonas Sundström
2, Hjalmar Granberg
2,
Jesper Edberg1, Ujwala Ail
1, Joseph Brill
3, Tom Lindström
2, Magnus Berggren
1 and Xavier Crispin1
1 Department of Science and Technology, Linköping University, Norrköping SE-60174, Sweden 2 Department of Physics and Astronomy, University of Kentucky, Lexington, KY40506-0055,
USA 3Innventia AB Box 5604, SE-11486 Stockholm, Sweden
E-mail: [email protected]; [email protected]
One of the first solid state ionic thermoelectric polymer demonstrated is a polyanion polystyrene
sulfonate PSS[1] displaying attractive thermoelectric properties. Ideally the ionic thermoelectric material
should be flexible, so that the ionic thermoelectric supercapacitor (ITESCs)[2] is able to conform the
shape of any hot/cold objects (for instance a pipe). Unfortunately polyelectrolytes are fragile and brittle. In
this work, we fabricate a polymer nano-composite using nanofibrillated cellulose NFC, and the
polyelectrolyte PSSNa and characterize its thermoelectric properties.[3] The NFC-PSSNa composite is
mechanically robust, foldable and flexible compared to PSSNa. Despite the presence of NFC, the ionic
conductivity and the ionic Seebeck coefficient of NFC-PSSNa is similar and even superior to PSSNa. This
new composite is the first demonstration of ionic thermoelectric paper. The mechanical properties of this
paper would enable to use roll-to-roll machine for production and assembling of large area ITESCs.
Figure 1. Thermoelectric properties of NFC-PSSNa composite film versus humidity and comparison with pure PSSNa.
[1] H. Wang, D. Zhao, Z. U. Khan, S. Puzinas, M. P. Jonsson, M. Berggren, X. Crispin, Adv. Electron. Mater.
2017, 3, 1700013.
[2] D. Zhao, H. Wang, Z. U. Khan, J. C. Chen, R. Gabrielsson, M. P. Jonsson, M. Berggren, X. Crispin,
Energy Envrion. Sci. 2016, 9, 1450-1457.
[3] F. Jiao, A. Naderi, D. Zhao, J. Schlueter, M. Shahi, J. Sundstrom, H. Granberg, J. Edberg, U. Ail, J. Brill,
T. Lindstrom, M. Berggren, X. Crispin, J. Mater. Chem. A 2017, 5, 16883-16888.
63
A9: Probing energy-dependent scattering in CuTe:PEDOT hybrid thermoelectric
films
Pawan Kumara, Eddy Zaiab, DV Maheswar Repakaa, Jeff Urbanb, Kedar Hippalgaonkara
a Institue of material research and engineering,
b Dept. of Chemical and Biomolecular Engineering UC Berkeley
Email: [email protected]
Hybrid (inorganic-organic) thermoelectric materials have been explored recently where large power factor
(S2) is found compared to each individual constituent[1]. The mechanism of enhancement is still under
intense debate as to whether transport occurs through the inorganic or via the organic parts. We have performed extensive temperature dependent thermoelectric transport studies on PEDOT:PPS-Cu doped Te nanowire hybrid system to explore the physics underlying the system. The data is analyzed using the charge
transport model recently developed by Kang and Snyder[2] for conducting polymers. The temperature
dependent conductivity shows that it is not activated transport but more indicative of hopping-like transport due to the strong influence of the polymer matrix. We confirm unequivocally the existence of energy dependent scattering in these hybrid materials and elucidate the difference from pure organic PEDOT:PSS matrix. Specifically, we show that the scattering of the holes in the hybrid system, defined by the energy- dependent scattering parameter (s), remains the same as the host polymer matrix. Interestingly, this does not change with a change in Copper loading within the Tellurium nanowires as well. An offset-compensated Hall measurement shows a large carrier concentration (n ~ 1020 cm-3), which supports our analysis that these samples are indeed degenerately doped. We hypothesize that the CuTe is doping the polymer matrix in a manner similar to electrochemical doping performed by Bubnova et al.,
[3] on a pure PEDOOT:PSS film. Our experiments prove, for the first time, that energy-dependent scattering is indeed playing a role in thermoelectric transport in hybrid films. The full suite of experiments and analysis in this work will prove useful in future studies of charge transport in similar hybrid thermoelectric material systems.
[1] K. C. See,⊥ J. P. Feser, C. E. Chen, A. Majumdar, J. J. Urban, and R. A. Segalman, Nano Lett. 10, 4664 (2010);
E.W. Zaia, A. Sahu, P. Zhou, M. P. Gordon, J. D. Forster, S. Aloni, Y. S. Liu, J. Guo, and J. J. Urban, Nano
Lett. 16, 3352 (2016); M. He, J. Ge, Z. Lin, X. Feng, X. Wang, H. Lu, Y. Yanga, and F. Qiu, Energy Environ.
Sci. 5, 8351 (2012); C. Z. Meng, C. H. Liu and S. S. Fan, Adv. Mater. 22, 535 (2010).
[2] S. D. Kang, and G. J. Snyder, Nat. Mater. 16, 252 (2017).
[3] Olga Bubnova, Magnus Berggren, and Xavier Crispin, J. Am. Chem. Soc. 134, 16456 (2012)
64
A10: More than 2 times improvement in the power factor of thermoelectric films
using liquid electrolytes
L. Márquez-García, B. Beltrán-Pitarch and J. García-Cañadas
Department of Industrial Systems Engineering and Design, Universitat Jaume I, Campus del Riu Sec,
12071 Castellón, Spain.
E-mail: [email protected]
The widespread application of thermoelectric (TE) materials is mainly limited by their low efficiency,
which is quantified by the dimensionless figure of merit ZT=σS2T/κ, where σ is the electrical conductivity,
S the Seebeck coefficient, T the temperature, κ the thermal conductivity, and σS2 the power factor (PF). In
the recent years, the performance of TE materials has been improved by nanostructuring which has allowed
a significant reduction in their thermal conductivity, but this parameter has now reached its (amorphous
materials) limit. This makes imperatively critical the enlargement of the PF in order to provide the high
efficiencies required by the technology. Although different strategies to improve the PF exist (e.g.
resonant levels, band convergence, modulation doping) they are usually difficult to implement, restricted to
only certain materials, and have provided not very large PF improvements.
Here we present a new concept in thermoelectricity, based on a hybrid system formed by a solid TE
material permeated by a liquid electrolyte.[1] The intimate solid/liquid contact in this hybrid system can
be designed to modify the electrostatic environment of the TE solid and provide significant PF enhancement.
The concept has been demonstrated in an Sb-doped SnO2 mesoporous film permeated with different inert
salts dissolved in 3-methoxypropionitrile, where the PF has been increased more than 3 times with respect
to the solid without electrolyte for a 1M LiBF4 salt. This improvement was produced by a significant
reduction (62%) of the electric resistance of the device without significantly affecting the Seebeck
coefficient.
On the other hand, ionic liquids were also employed as electrolytes. In this case, the electrical
resistivity showed a more significant decrease of 82% when 1-Butyl-3-methylimidazolium iodide was
employed. However, the Seebeck coefficient was reduced by 35%, finally resulting in an average 2.4 times
enhancement of the PF. These results establish a new strategy for the significant improvement of the PF
which is not restricted to certain materials and can be potentially applied widely
[1] L. Márquez-García, B. Beltrán-Pitarch, D. Powell, G. Min, J. García-Cañadas, Large power factor
improvement in a novel solid-liquid thermoelectric hybrid device, submitted for publication.
65
A11: Water-resistant Polymer Organic Thermoelectric Devices
Jae Gyu Jang1, Yongjun Jeon
1, Jong-In Hong
1, and Sung Hyun Kim
2
1Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea. 1Department of Carbon Fusion Engineering, Wonkwang Univeristy, Iksan, Jeonbuk 54538,
Republic of Korea.
E-mail: [email protected]
Conventional conducting polymers is a promising organic-thermoelectric active material due to its high
electrical conductivity.[1]
In particular, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)
(PEDOT:PSS) is one of the most widely studied as a thermoelectric active material because its electrical
conductivity can be increased to over 4000 S cm-1
by increasing the interconnected conductive pathways[2]
Along with the tremendous research of PEDOT:PSS, the thermoelectric properties of them has significantly
improved in the last few years.[3]
However, there is few systematic study of the stability of thermoelectric
devices under humid environment.[3]
In case of PEDOT:PSS, PSS is an water-soluble anionic
polyelectrolyte and therefore, thermoelectric performance of PEDOT:PSS is very sensitive tohumid
atmosphere.[4]
In addition, hygroscopic PSS readily deforms PEDOT:PSS films under high humidity
environment,[5]
leading to not only degrade its intrinsic conductivity but also lose its capability for
thermoelectric applications. Stability of organic materials is key issues in field of organic electronics.[6-7]
Thus,
it is needed to improve the stability of organic thermoelectric devices under humid environment.
In this research, we improved the humid stability and thermoelectric properties of PEDOT:PSS films
through two approaches. First, we introduced Iso-sorbide derivatives as a hydrophilic additive to inducethe
structural and morphological evolution of the films. The films showed the increase of mechanical
property, leading to enhance the water-resistance/humid stability of thermoelectric devices. Second, we
modified hygroscopic PSS via post glycerol vapor treatment. The cross-linking reaction between glycerol
vapor and PSS affords hydrophobic characteristics on the PEDOT:PSS films. The details will be explained
in the presentation. We expect that our systematic studies respect to humid-stability of PEDOT:PSS and
thermoelectric properties will provide an opportunity for practical application of organic thermoelectric
devices under humid environment.
[1] Q. S. Wei, M. Mukaida, K. Kirihara, Y. Naitoh, T. Ishida, Materials, 2015, 8, 732-750. [2] Y. Xia, K. Sun,
J. Ouyang, Adv. Mater. 2012, 24, 2436-2440.
[3] B. Russ, A. Glaudell, J.J. Urban, M.L. Chabinyc, R.A. Segalman, Nat. Rev. Mater., 2016, 1, 16050.
[4] Kim, G.-H., Kim, J., Pipe, K.P, Appl. Phys. Lett., 2016, 108, 093301-093305.
[5] K. Muro, M. Watanabe, T. Tamai, K. Yazawa, K. Matsukawaa RSC Adv., 2016, 6, 87147- 87152.
[6] K. Lee, J. Y. Kim, S. H. Park, S. H. Kim, S. Cho, A. J. Heeger, Adv. Mater., 2007, 19, 2445- 2449.
[7] Jorgensen, M., Norrman, K., Krebs, F. C., Sol. Energ. Mat. Sol. Cells. 2008, 92, 686-714.
66
A12: A New Type of Conducting Polymers for Thermoelectric Application
Dafei Yuan, Liyao Liu, Wei Xu, Xiaozhang Zhu,* and Daoben Zhu
Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
E-mail: [email protected]
Conducting polymers have shown great potentia ls in the application as thermoelectric materia ls. In a few
years, thermoelectric performances have been significantly enhanced, and a ZT value as high as 0.42 was
obtained with the classical conducting polymers PEDOT-PSS. However, this value is still not enough for
practical applications. Developing new conducting polymers would provide new opportunities for better
understanding the structure-property relationships in thermoelectric materia ls and continually enhancing the
thermoelectric performance. In this work, a new family of organic conducting polymers PTbT-Tos are
prepared by in-situ polymerization.[1]
Through careful optimizations, the electrical conductivities can be
enhanced to 450 S cm–1
. In comparison with the metallic properties of PEDOT-Tos with elevated
temperature, [2]
the electrical conductivity of PTbT- Tos is increased by over one order of magnitude from
300 K to 400 K. Moreover, these conducting polymers show great prospect as thermoelectric materials. A
high power factor of 500 μW m–1
K–1
is achieved by PTbT-Tos at 400 K.
Figure 1. The resistances of PEDOT-Tos and PTbT-Tos with elevated temperatures.
[1] T. Park, C. Park, B. Kim, H. Shin, E. Kim, Energy Environ. Sci. 2013, 6, 788.
[2] O. Bubno0076a, Z. U. Khan, H. Wang, S. Braun, D. R. Evans, M. Fabretto, P. Hojati- Talemi, D.
Dagnelund, J. B. Arlin, Y. H. Geerts, S. Desbief, D. W. Breiby, J. W. Andreasen, R. Lazzaroni, W. M.
Chen, I. Zozoulenko, M. Fahlman, P. J. Murphy, M. Berggren, X. Crispin, Nature Mater. 2014, 13,
190.
67
A13: Polar Side Chains Enhance Processability, Electrical Conductivity, and
Thermal Stability of a Molecularly p-Doped Polythiophene
Renee Kroon1, David Kiefer
1, Dominik Stegerer
2, Liyang Yu
1, Michael Sommer
2, and Christian Müller
1
1 Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296,
Göteborg, Sweden
2 Faculty of Natural Sciences, Chemnitz University of Technology, 09111, Chemnitz, Germany
E-mail: [email protected]
Molecular doping of organic semiconductors is critical for optimizing a range of optoelectronic devices
such as field-effect transistors, solar cells, and thermoelectric generators. However, many dopant:polymer pairs
suffer from poor solubility in common organic solvents, which leads to a suboptimal solid-state nanostructure
and hence low electrical conductivity. A further drawback is the poor thermal stability through sublimation of
the dopant. The use of oligo ethylene glycol side chains is demonstrated to significantly improve the
processability of the conjugated polymer p(g42T-T)—a polythiophene—in polar aprotic solvents, which
facilitates coprocessing of dopant:polymer pairs from the same solution at room temperature. The use of
common molecular dopants such as 2,3,5,6- tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) and 2,3-
dichloro-5,6-dicyano-1,4- benzoquinone (DDQ) is explored. Doping of p(g42T-T) with F4TCNQ results in an
electrical conductivity of up to 100 S cm−1
. Moreover, the increased compatibility of the polar dopant
F4TCNQ with the oligo ethylene glycol functionalized polythiophene results in a high degree of thermal
stability at up to 150 °C.[1]
[1] R. Kroon, D. Kiefer, D. Stegerer, L. Yu, M. Sommer, C. Müller, Adv. Mater. 2017, 29, 1700930.
68
A14: Multi-layering in thin film organic thermoelectrics: the hidden gem
Virgil Andrei1,2
, Kevin Bethke1, Klaus Rademann
1
1Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489, Berlin, Germany 2Current address: University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK E-mail:
Due to their highly tunable electronic properties, the interest in the versatile conductive polymers has
expanded beyond photovoltaics,[1]
standing out alongside oxide- or carbon-based compounds[2]
as some of
the most promising thermoelectric materials. Even though existing concepts can provide a good
understanding of their transport properties, the values reported for the electrical conductivity and Seebeck
coefficient still vary over wide ranges. While factors such as the synthesis procedure, the sample preparation
and the type of doping are known to affect these values, our data indicates that a multilayered deposition may
also contribute to an unexpected improvement in the electrical conductivity of the films.[3]
Additionally, we
take a look at the latest breakthroughs from the field of polymer composites, which revolve around the use
of PEDOT:PSS/PANI multilayers. While the pioneering works of 2016 indicate that a complex structure is
required to obtain significant enhancements,[4,5]
we reveal how a high performance can be maintained even
when reducing the material’s complexity. On this occasion, we introduce the concept of in situ
complementary doping, revealing how a rational design of the chemical interactions between the
PEDOT:PSS and PANI chains can lead to a conductivity improvement for both components.[6]
A mechanistic
model is also proposed to explain the newly observed strain-induced effects, including the multiscale
folding and film shrinkage (see Fig. 1). These exciting findings offer a glimpse of the next generation thin-
film thermoelectrics, which could involve self-sustained ultra-thin membranes.
Fig. 1: Model for the chain reorganization within alternating PANI base and PEDOT:PSS layers, which causes
the conductivity improvements and topology effects.
[1] V. Andrei, K. Bethke, K. Rademann, Energy Environ. Sci., 2016, 9, 1528-1532.
[2] V. Andrei, K. Bethke, K. Rademann, Phys. Chem. Chem. Phys., 2016, 18, 10700-10707.
[3] V. Andrei, K. Bethke, F. Madzharova, S. Beeg, A. Knop-Gericke, J. Kneipp, K. Rademann, Adv.
Electron. Mater., 2017, 3, 1600473.
[4] C. Cho, K. L. Wallace, P. Tzeng, J.-H. Hsu, C. Yu, J. C. Grunlan, Adv. Energy Mater., 2016, 6,
1502168.
[5] H. J. Lee, G. Anoop, H. J. Lee, C. Kim, J.-W. Park, J. Choi, H. Kim, Y.-J. Kim, E. Lee, S.-G. Lee, Y.-M.
Kim, J.-H. Lee, J. Y. Jo, Energy Environ. Sci., 2016, 9, 2806–2811.
[6] V. Andrei, K. Bethke, F. Madzharova, A. C. Bronneberg, J. Kneipp, K. Rademann, ACS Appl. Mater.
Interfaces, 2017, 9, 33308–33316.
69
A15: Optimization of polymer thermoelectrics via doping gradient
Osnat Zapata-Arteaga, Bernhard Dörling, and Mariano Campoy-Quiles
Institute of Materials Science of Barcelona (ICMAB-CSIC), Campus of the UAB, 08193 Bellaterra,
Spain
E-Mail: [email protected]
Accurate control of the doping level is vital for the optimization of polymer semiconductors towards highly efficient thermoelectrics. Because of the large number of promising polymers and dopants,
combined with the numerous possible doping techniques, optimization is a time consuming process. Vertical
and lateral gradient doping is an encouraging approach used to optimize device performance in the field
of organic solar cells (OSC).[1] It is clear that the same approach could be used to fine tune the doping level
and optimize the power factor (PF) in organic thermoelectric (OTE) applications.[2] Moreover, several
techniques for achieving lateral composition and thickness gradients have been developed in the OSC field,[3]
which may aid in the fabrication and evaluation of doping gradients in polymer films for OTE. Nonetheless,
the fabrication of samples with a lateral gradient samples is still considered a difficult task, which requires precise control of diffusion rates and processing techniques.
In this work, we present a straightforward method for obtaining a lateral doping gradient in thin polymer
films. The characterization of the Seebeck coefficient (S), electrical conductivity () and thermal
conductivity () is then performed over discrete quasi-homogeneous sections. This fast approach gives a better insight in the mechanisms of doping, as well as providing a viable tool for the optimization of OTE. Moreover, it is a viable alternative to techniques such as PDMS transfer, layer- by-layer
deposition, co-deposition and optical de-doping processes reported in the literature on lateral doping of organic
semiconductors.[1]
Figure 1. P3HT film vapor-doped with F4TCNQ. Exposure to the dopant increased stepwise from left to right.
[1] Jacobs, I. E. & Moulé, A. J. Adv. Mater. 2017, https://doi.org/10.1002/adma.201703063.
[2] Jung, I. H. et al. Sci. Rep. 2017, 7, 44704.
[3] Rodríguez-Martínez, X. et al. J. Mater. Chem. C, 2017, 5, 7270–7282.
70
A16: Flexible Self-powered Sensors Using Organic Thermoelectric Effect
Kening Wan1, Prospero Taroni Junior
1, Zilu Liu
2, Bob C Schroeder
2 and Emiliano Bilotti*1
1School of Engineering and Material Sciences, Queen Mary University of London, Mile End Road,
E1 4NS, London, UK 2School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, E1
4NS, London, UK
E-mail: [email protected]; [email protected]
With the development of ‘smart’ devices, soft robotics and internet-of-things, novel flexible and especially
autonomous sensors will be indispensable. Flexible organic thermoelectric materials could help meeting these
technological requirements, particularly for self-powered sensors. Recently promising results have been
published on the thermoelectric properties of conductive polymers. PEDOT has been demonstrated to be the
best performing p-type conductive polymer [1-3]
. Unfortunately, n-type organic thermoelectric materials are
more challenging because of their poor environmental stability and low electrical conductivity. Recently, a
new n-type organic thermoelectric material [4-6]
was shown to possess the best compromise between Seebeck
coefficient and electrical conductivity. Unfortunately, it still suffers from limited toughness and processability.
Figure 1. (A) Thermoelectric properties of PU/Nax(Ni-ett)n blends. (B) The tensile properties for self-standing
PU/Nax(Ni-ett)n composites films. (C) Self-powered strain sensing cyclic test results, self-powered by Seebeck
voltage due to the temperature difference between the two clamps without external voltage supply.
Herein, we propose a strategy to overcome these limitations. We demonstrate that blending Nax(Ni-ett)n
with a commercial polyurethane (PU) (Lycra®), an easily processable, stretchable and tough film, with self-
powered sensing capabilities, could be obtained. A flexible and stretchable self- powered sensor device was
been developed by combining this n-type ‘leg’ in series with an analogous p-type ‘leg’, based on PU/PEDOT.
This device can fit different requirements, with potential applications in e-skin, soft robotics and wearable
electronics. We will ultimately utilize the voltage generated by a temperature gradient to sense a wide variety
of stimuli including strain, pressure, humidity, light, and others.
[1] F. Zhang, Y. Zang, D. Huang, C.-a. Di and D. Zhu, Nature communications, 2015, 6, 8356.[2] M. Culebras, C. M. Gómez and A. Cantarero, Mater., 2014, 7, 6701-6732.[3] O. Bubnova and X. Crispin, Energy & Environmental Science, 2012, 5, 9345 -9362.[4] Y. Sun, P. Sheng, C. Di, F. Jiao, W. Xu, D. Qiu and D. Zhu, Adv Mater, 2012, 24, 932 -937.[5] D. D. Freeman, K. Choi and C. Yu, PloS one, 2012, 7, e47822.[6] M. Piao, G. Kim, G. P. Kennedy, S. Roth and U. Dettlaff -Weglikowska, physica status solidi (b), 2013,
250, 1468-1473.
71
A17: Conducting Polymer Nanoparticles Prepared by Miniemulsion
Polymerization: Pros and Cons for Thermoelectric Applications
Mario Culebras1,2
, José F. Serrano-Claumarchirant2, Juan F. Ferrer-Crespo
2, Amparo Sánchez-Soler
2, Maria J.
Sanchis3, Andrés Cantarero
4, Clara M. Gómez
2, Rafael Muñoz-Espí
2
1 Stokes Laboratories, Bernal Institute, University of Limerick, Ireland
2 Institute of Materials Science (ICMUV), Universitat de València, Spain
3Dept of Applied Thermodynamics,Universitat Politècnica de València, Valencia, Spain
4 Institute of Molecular Science (ICMol), Universitat de València, Spain
E-mail: [email protected]
Conducting polymers have been attracting an increasing attention of the energy-materials community over the
last decade, mainly due to their easier processing, when compared to inorganic counterparts. The main
advantages of conducting polymers are the low cost of the raw materials, their flexibility, their easy chemical
modification, and their versatility in a wide range of applications. It is therefore not surprising that they are
being used in different energy-related devices, including thermoelectric applications. However, the increase of
the thermoelectric efficiency of conducting polymers, to make them competitive with traditional inorganic
thermoelectric materials, remains a challenge. In this context, nanostructuration methods can be a powerful
tool to improve their performance for energy applications [1].
A simple way to produce nanoparticles of conducting polymers is, in principle, the use of colloidal methods.
Soft-template methods, especially those based on the miniemulsion technique, have been employed to
synthesize stable polymer particle suspensions of a wide range of materials, including polystyrene,
poly(mehtyl methacrylate) or polyurethane. Unfortunately, the synthesis of conducting polymer nanoparticles
by oxidative polymerization is much more complicated, because the addition of oxidizers may compromise
the colloidal stability of the system. In this communication, we will report the successful synthesis of stable
poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles with a well-defined spherical morphology (size
around 35 nm). By using analogous experimental conditions, polyaniline and polypyrrol nanoparticles can
also be prepared. The stable suspensions are used for the preparation of films with defined electrical
properties.
[1] M.Culebras, C. Gómez and A. Cantarero, Materials. 2014, 7 , 6701-6732.
72
A19: Hybrid Effect for Thermoelectric Enhancement and Development of
Flexible Modules
Takao Mori and Norifusa Satoh
International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials
Science (NIMS), Tsukuba, 305-0044, Japan
E-mail: [email protected]
Novel materials and principles are being utilized in the search for viable thermoelectrics (TE) [1]
. While
developing an n-type counterpart to p-type boron carbide, we previously discovered an interesting effect.
Through a combination of doping certain transition-metals (Co or V) into YB22C2N and heat treatment,
Seebeck coefficients, , could be enhanced by 220% while simultaneously, electrical conductivity, , was
increased by ~10,000% [2]
. This was striking since it largely overcomes the traditional trade-off between and
, a large obstacle for enhancing TE performance. Nano-characterization indicates that this is due to a
hybrid/composite effect where highly conductive paths were established in the material of which the host
material assumedly has its electronic structure modified by intrinsic doping [3]
. This hybrid effect may be
applicable to a broad spectrum of thermoelectric materials, both inorganic and organic hosts, and recent
developments will be presented.
We have also been trying to develop new ways to fabricate flexible TE modules. The Seebeck effect
typically generates tens of µV. To drive conventional electric devices, it is necessary to pattern and connect
more than one hundred cells as a TE module. We have utilized photolithography to pattern organic TE cells.
One-leg TE modules were first readily fabricated via printing the bottom electrode pastes, organic TE
materials, and the upper electrode pastes. In order to maintain the temperature difference by separating the
upper and bottom electrodes, we fabricated π-type thermoelectric modules via fulfilling n-type and p-type TE
materials into photolithographically patterned resists. Figure 1 shows the module pattern we designed, 13 × 13
cells in 40 × 40 mm2. We prepared p-type and n-type TE materials based on poly(3,4-ethylenedioxy thiophene)
polystyrene sulfonate[4]
and tetrathiafulvalene 7,7,8,8-tetracyanoquinodimethane salt [5]
, respectively. Overall,
we re-arrange well-established fabrication processes, such as photolithography, fulfilling, and electrode
deposition, to emergently fabricate organic π-type TE modules. Details of the module performances will also
be reported.
Figure 1. Design of organic π-type thermoelectric module: (a) the thermoelectric layer, (b) the upper electrode,
and (c) the bottom electrode.
[1] T. Mori, Small 2017, in press doi: 10.1002/smll.201702013.
[2] A. Prytuliak et al., J. Electron. Mat. 2011, 40, 920, Mat. Res. Bull. 2013, 48, 1972.
[3] T. Mori and T. Hara, Scr. Mater. 2016, 111, 44.
[4] Kim et al., Nat. Mater. 2013, 12, 719.
[5] Bubnova et al., Nat. Mater. 2011, 10, 429.
73
A20: Temperature Dependence of Seebeck Coefficient in Ionic Liquids
Laure Jeandupeux1, Edith Laux
1, Stefanie Uhl
1, Herbert Keppner
1
1Haute Ecole Arc Ingénierie (HES-SO), Eplatures-Grise 17, 2300 La Chaux-de-Fonds, Switzerland
E-mail: [email protected]
Ionic liquids (ILs) are interesting candidates as thermoelectric materials, especially their low thermal
conductivity. For thermoelectricity based on ionic liquids, different kinds of temperature related Seebeck
coefficient (SE) behavior have been encountered. In order to determine SE, a cell was filled with IL, and a
temperature gradient was applied between two electrodes, allowing the measurement of a voltage. Over the
course of multiple experiments [1-3]
, it was seen that ILs give the same voltage variation for all temperature
gradients, or constant SE. However, some ILs (e.g. propylammonium nitrate) only develop a linear
behavior (constant SE) over some specific temperature ranges, and can even change the sign of SE. Those
experiments with specific temperature ranges have allowed SE as high as 12mV/K, and adequate power
output. Moreover, it was seen that some ILs (e.g. tetrabutylammonium tetrafluoroborate TBA-BF4) can
undergo a linear SE increase with respect to rising temperature (Fig. 1). It is assumed that there is a strong
temperature dependent change in the ion attachment at the electrode surfaces.
Looking at IL that undertake a phase transition during SE measurements (e.g. ethylammonium
tetrafluoroborate EA-BF4), it was shown that SE changes sign close to the phase transition temperature,
and the SE value varies tremendously (Fig. 2). This changes could be explained by the creation of an ad-
layer which allows a modified ion attachment behavior. This ad-layer has a huge impact by increasing the
electrode reactive surface and therefore modifying the ion attachment at the interface.
Those unexpected behaviors open the door to a complete new set of experiments, leading to liquid tailoring
for specific applications.
Figure 1. SE ofTBA-BF4, increasing linearly as ΔT rises. Figure 2. SE of a phase-changing EA-BF4. A change of SE-sign is visible near transition temperature
[1] S. Uhl , E. Laux, T. Journot, L. Piervittori, L. Jeandupeux and H. Keppner, JECM, 2016, 3, 42-50
[2] H. Keppner, S. Uhl, E. Laux, L. Jeandupeux, J. Tschanz and T. Journot, Mater. Today:
Proceedings, 2015, 2, 680-689
[3] E. Laux, S. Uhl, T. Journot, J. Brossard, L. Jeandupeux and H. Keppner, J. Electron. Mater., 2016,
45, 7 (2016) 3383-3389
74
A21: Flexible PEDOT:PSS & Polypyrrole nanoparticles Co-coated Cotton Fabric
Thermoelectric Films
Yong Du1,2
, Biplab Paul2, and Per Eklund
2
1 School of Materials Science and Engineering, Shanghai Institute of Technology, 100 Haiquan Road,
Shanghai 201418, PR China 2 Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping
University, SE-58183 Linköping, Sweden
E-mail: [email protected] or [email protected]
Flexible PEDOT:PSS & polypyrrole nanoparticles co-coated cotton fabric thermoelectric films were
prepared by in-situ polymerization combining dip coating process. Compared to pure polypyrrole
nanoparticles coated cotton fabric, both electrical conductivity and Seebeck coefficient of the PEDOT:PSS
& polypyrrole nanoparticles co-coated cotton fabric are enhanced. Furthermore, the electrical conductivity
and Seebeck coefficient of the PEDOT:PSS & polypyrrole nanoparticles co- coated cotton fabric are
increased as the measured temperature increasing from 300 K to 375 K. The thermal conductivity of the
PEDOT:PSS & polypyrrole nanoparticles co-coated cotton fabric is about one or two orders of magnitude
lower than that of the traditional inorganic thermoelectric materials. This is a facile method to endow cotton
fabric with TE properties, and also to enhance the TE properties of polypyrrole nanoparticles coated cotton
fabric. This method can be applied to other conducting polymers and substrates.
75
A22: Metallo-Organic Polymers and Devices for Thermoelectric Energy
Harvesting
Akanksha K. Menon1, Rylan Wolfe
2, Kiarash Gordiz
1, Hend Elmoughni
1, John R. Reynolds
2 and Shannon K. Yee1
1 George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta,
GA, USA
2 School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, USA
E-mail: [email protected]
Organic thermoelectric (TE) generators have the potential for low-grade waste heat recovery and energy
harvesting. These devices can be fabricated via printing processes that are low cost from materials that are
lightweight and flexible. In the past decade, significant progress has been made with high performing p-type
materials based on PEDOT and its derivatives. The primary challenge for n-type organic materials is their air
stability and achieving a sufficiently high electrical conductivity (σ) via doping without decreasing the
Seebeck coefficient (S). Metallo-organic polymers are a suitable class of n-type polymers that maintain their
stability in air. In this work, we report the synthesis, characterization and thermoelectric properties of
poly(nickel-ethenetetrathiolate) or Ni-ETT and poly(nickel- tetrathiooxalate) or Ni-TTO that are intrinsically
electrically conducting and n-type. These polymers form as infusible black powders and are dispersed in a
poly(vinylidene fluoride) matrix to fabricate films. By modifying the reaction conditions (counterion, Ni
equivalents and oxidation states), we investigate the extent to which S and σ can be enhanced. We also report
the effects of annealing films which results in a further increase in the Seebeck coefficient. The temperature
dependent properties for these polymers show thermally-activated behavior that is consistent with hopping
transport, where both σ and S increase with temperature.
As a parallel effort to developing materials, there is a need for new device designs that leverage the benefits
of conducting polymers, i.e., their low thermal conductivity and solution processability.
Polymer device prototypes have been limited to traditional flat-plate geometries which suffer from low
power densities, large contact resistances and the need for active cooling. To overcome these challenges, we
propose two new device architectures for organic TEs using our n-type ETT and commercial PEDOT:PSS.
Based on characteristic thermal length scales for polymers, we demonstrate a radial device that consists of
alternating disks of p-type and n-type polymers stacked coaxially. The radial design enables heat spreading
which eliminates the need for active cooling, while also reducing electrical contact resistance thereby enabling
higher power densities. In our second design, we propose a close-packed layout for printing high fill factor
devices with fractal space-filling curves as interconnect patterns; this allows for load matching to a variety of
applications. These novel architectures could potentially enable rapid scalability onto flexible substrates and
fabrics at low $/W costs for self-powered sensors and wearable electronics.
Figure 1. New device architectures for polymer-based TE generators
76
A23: Preparation and Thermoelectric Properties of PEDOT/PSS-HNTs Hybrid
Thin Films
Hu Yan
College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, China
E-mail: [email protected]
Poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS), one of the most successfully commercialized conducting polymers, has attracted wide attentions from both academia and industries because of the excellent conductivity, transparency and thermal stability coupled with the merit of the wet-
process in a low cost.[1]
Hybridization with carbon nanotubes also is a common strategy to improve both
conductivity and mechanical properties of the PEDOT/PSS thin films.[2]
On the other hand, Halloysite nanotubes (HNTs) have also attracted much attention due to their molecule- storage ability, excellent mechanical strength and thermal stability. The HNTs consist of one alumina octahedron sheet and one silica tetrahedron sheet at a 1:1 stoichiometric ratio, both sheets bending as double layers into hollow nanotubular
structure in the submicrometer range and having a large specific surface area.[3]
Recently we have for the first time found that completely insulating HNTs significantly enhance the electrical conductivity of PEDOT/PSS films by simple mixing the HNTs and PEDOT/PSS. Based on this accidental finding, we have created highly porous and conductive PEDOT/PSS films hybridized with the
HNTs.[4]
We have investigated an electromagnetic interference (EMI) and thermoelectric (TE) properties of the PEDOT/PSS-HNTs hybrid films. On the one hand, the hybridization of the HNTs induced the EMI properties for the pristine PEDOT/PSS films and the content of the HNTs in the hybrid films significantly influenced the EMI properties of the hybrid films, indicating that PEDOT/PSS inserts into channels of the HNTs to form highly conductive
PEDOT/PSS domains with high aspect ratio. The highest EMI shielding effectiveness of the hybrid film is -
16.3 dB in the measured frequency range from 2 to 13 GHz.[5]
On the other hand, thermoelectric figure of merit (ZT) values of the PEDOT/PSS-HNTs hybrid films, which were calculated using the corresponding
electrical conductivity, Seebeck coefficient and thermal conductivity, were in the range of 1.3-5.5 x 10-3
at 300K, comparable with those of conventional conducting polymers although the hybrid films containing the
insulating HNTs in 75 w%.[6]
Herein we present the preparation and thermoelectric properties of the PEDOT/PSS-HNTs hybrid thin
films with a large-area and submicrometer-thickness. [7]
[1] X. Crispin, F. L. E. Jakobsson, A. Crispin, P. C. M. Grim, P. Andersson, A. Volodin, C. van
Haesendonck, M. Van der Auweraer, W. R. Salaneck, M. Berggren, Chem. Mater., 2006, 18, 4354- 4360.
[2] D. J. Yun, K. P. Hong, S. H. Kim, W. M. Yun, J. Y. Jang, W. S. Kwon, C. E. Park, S. W. Rhee, ACS Appl.
Mater. Interfaces, 2011, 3, 43-49.
[3] E. Joussein, B. Delvaux, S. Petit, J. Churchman, B. Theng, D. Righi, Clay Minerals, 2005, 40, 383-426.
[4] H. Yan, P. Zhang, J. Li, X. L. Zhao, K. Zhang, B. Zhang, Sci. Rep., 2015, 5, 18641.
[5] S. J. Luo, P. Zhang, Y. A. Mei, J. B. Chang, H. Yan, J. Appl. Polym. Sci., 2016, 133, 4424.
[6] S. J. Luo, P. Zhang, Y. A. Mei, J. B. Chang, S. Ichikawa, K. Oshima, N. Toshima, H. Yan, Current
Nanosci., 2017, 13, 130135.
[7] H. Yan, J. Li, H. L. She, C. Y. Zhu, K. Oshima, N. Toshima, unpublished data.
77
A24: Thermoelectric properties of organic donor-acceptor copolymers investigated
by electrolyte gating
Kaito Kanahashi1, Naoya Takekoshi
2, Yong-Young Noh
3, Hiromichi Ohta
4, Hisaaki Tanaka
2 and Taishi
Takenobu1,2
1 Department of Advance Science and Engineering, Waseda Univ., Tokyo 169-8555, Japan 2 Department of Applied Physics, Nagoya University, Nagoya 464-8603, Japan
3 Department of Energy and Materials Engineering, Dongguk University, Seoul 04620, Republic of
Korea 4 Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan
E-mail: [email protected]
Although organic conducting polymers are promising materials for future flexible and stretchable
thermoelectric devices due to their excellent flexibility and processability, their thermoelectric properties, such
as conductivity (σ) dependences of Seebeck coefficient (S) and power factor (PF), have not been fully
understood yet. In 2015, Glaudell et al. investigated the conductivity dependence of Seebeck coefficient in
chemically doped organic conducting polymers and they have reported the relationship of S ~ σ−1/4
.[1]
However, this relationship is not explained by simple transport mechanisms, such as variable hopping and
thermal activation theories. On the other hand, in 2017, Kang et al. pointed out that the same data set is
explained by the combination of S σ−1/3
(band transport) and S lnσ (thermal activation behavior).[2]
Very
importantly, in chemically doped organic conducting polymers, we must compare different samples with
different doping process and it makes the fair comparison very difficult. To overcome this problem, we
focused on the electrolyte gating technique, in which one can control the conductivity of organic polymer films
widely and continuously just by voltage application.[3]
Therefore, in this study, we investigated thermoelectric
properties of organic conducting polymers by using electrolyte gating method.
As the target materials, we selected donor-acceptor copolymers (DPPT-TT, PDPP3T and PDPP4T) and
PBTTT. Figure 1 shows the conductivity dependences of S and PF in all materials and the relationship of S
σ−1/4
was clearly obtained. PF was nicely optimized by electrolyte gating method, which is very important to
compare thermoelectric properties of different materials. Interestingly, in higher conductivity region, we
observed the different trends and this feature is firstly reported. To gain more information, we also
investigated the aligned DPPT-TT films and highly crystallized PBTTT films, prepared by off-center coating
and OTS treatment, respectively. As shown in Fig. 1, these treatments drastically change the conductivity
dependences, suggesting the importance of domain structure quality.
Fig. 1. Conductivity dependences of S and PF.
[1] A. M. Glaudell et al., Adv. Energy Mater. 2015, 5, 1401072.
[2] S. D. Kang et al., Nat. Mater. 2017, 16, 252.
[3] J. Pu, K. Kanahashi et al., Phys. Rev. B. 2016, 94, 014312.
78
A25: Investigating on the Intrinsic Charge Transport in Poly(3- hexylthiophene)
by Regulating the Molecular Structure
Sanyin Qu, Qin Yao and Lidong Chen
Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050, China
Organic conjugated polymers possess unique features for application as thermoelectric (TE) materials
because of their low thermal conductivity, low density and low cost due to rich levels of resources, easy
synthesis and facile processing into versatile forms as compared with inorganic semiconductor materials. The
charge transport behaviors, including the transport edge, the dimensionality of the transport path and charge
carrier mobility, have been identified the most critical factor for the performance of organic TE materials. The
underlying parameters, which may determine the charge transport properties, include the molecular/electronic
structure as well as the packing and/or alignment of polymer chains. Poly(3-hexylthiophene) (P3HT) is a
widely studied organic semiconductor with highly tunable molecular structure and molecular weight compared
to other conducting polymers. In this report, we take P3HT as a model structure, to investigate the effect of
polymer structures including the side chain substitution and chain length on the charge transport
properties of P3HT. This work would formulate design rules for rational modification of polymer
structures and assist in the design of high performance organic TE materials.
[1] Sanyin Qu, Qin Yao, Huarong Zeng, Ctirad Uher and Lidong Chen. NPG Asia Mater, 2016, 8, e292.
[2] Sanyin Qu, Qin Yao, Wei Shi, Liming Wang and Lidong Chen. J. Electron. Mater., 2016, 45, 1389.
[3] Wei Shi, Qin Yao, Sanyin Qu, Hongyi Chen, Tiansong Zhang and Lidong Chen. NPG Asia Mater,
2017, 9, e405.
79
A26: Boost the N-Type Thermoelectric Performance of Diketo- pyrrolopyrrole-
Based Polymers Through Backbone Engineering
Chi-Yuan Yang1, Yi-Fan Ding1, Wen-Long Jin
2, Chong-An Di
2*, Jie-Yu Wang
1*, and Jian Pei
1*
1 Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic
Chemistry and Molecular Engineering of the Ministry of Education, Center of Soft Matter Science and
Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871,
China. 2 Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids,
Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
E- mail: [email protected], [email protected], [email protected]
Compared with their p-type counterparts, n-type polymer thermoelectric materials showed much
lower performance largely due to inefficient doping and thereby lower conductivity. In the past few
years, Diketopyrrolopyrrole(DPP)-based conjugated polymers have been extensively studied for polymer
field-effect transistors and solar cells because of their high charge carrier mobilities and high power
conversion efficiency. To date, DPP polymers have exhibited good p-type conductivity, however, their n-type
conductivity has not been reported yet. Herein, for the first time, high conductivity and high thermoelectric
performance in DPP polymers is realized by introducing fluorine atoms on the donor part of a DPP
polymer. In contrast with the non-fluorine substituted polymer that only showed an n-type conductivity
of 1×10−3
S/cm, the fluorine-substituted DPP polymer exhibited conductivities over 1 S/cm. This value is
almost three orders of magnitude higher than non-engineered DPP polymers, which is among the best
results for solution-processed polymer, n-type polymer thermoelectric materials. We found that fluorine
substitution not only provides the DPP polymer with lower LUMO levels, locked conformation, and
higher electron conductivity, but also enhances the n-doping efficiency, enlarges the anion polaron
delocalized length and significantly reduces the phase separation. Our findings demonstrate that proper
backbone engineering can greatly improve the n-type thermoelectric performance of conjugated polymers.
Figure 1. Chemical structures of DPP-based conjugated polymer and improvement of their n-type
thermoelectric performance after backbone engineering.
80
A27: The influence of dynamic disorder on the vibrational and thermal properties
of hybrid perovskites
Aurélien M. A. LeguY1, Xabier Rodríguez-Martínez
2, Adrián Francisco López
2, Jarvist M. Frost
1,3, Jonathan
Skelton3, Federico Brivio
3, Bethan Charles
3, Oliver J. Weber
3, Anuradha Pallipurath
4, M. Isabel Alonso
2,
Mariano Campoy-Quiles2, Mark T. Weller
3, Jenny Nelson
1,5, Aron Walsh
1,3, Piers R.F. Barnes
1 & Alejandro
R. Goñi2,6
1Physics department, Imperial College London, UK, SW7 2AZ 2Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra,
Spain 3Chemistry department, University of Bath, UK, BA2 7AY
4School of chemistry, National University of Ireland Galway, Ireland 5SPECIFIC, College of Engineering, Swansea Uni., Baglan Bay Innovation and Knowledge Centre,
UK, SA12 7AX
6ICREA, Passeig Lluís Companys 23, 08010 Barcelona, Spain
E-mail: [email protected]
Organic-inorganic perovskites have irrupted in the field of photovoltaics as the base for production of
solution-processed solar cells, reaching power-conversion efficiencies in excess of 20% in 2015. Raman
spectroscopy can characterize in-situ chemical environments in materials and reveal the nature of lattice
vibrations (phonons). Here we report Raman spectra of hybrid lead halide single crystals (APbX3, X=I, Br, Cl,
A=MA methylammonium, FA formamidinium) at temperatures between 80 and 370 K and compare them with
results of density-functional-theory phonon calculations [1]
. The good agreement between experimental spectra
and calculated vibrational modes enables confident assignment of most of the vibrational features between 50
and 3500 cm-1
[2]
. Reorientation of the MA and/or FA cations, unlocked in their cavities at the orthorhombic-
to-tetragonal phase transition, plays a key role in shaping the vibrational spectra of the different compounds.
Calculations show that these dynamic effects split Raman peaks and create more structure than predicted from
the independent harmonic modes, explaining extra peaks present in experimental spectra; a source of confusion
in earlier studies. From the analysis of the Raman mode linewidths, it is found that MAPbI3 shows
exceptionally short phonon lifetimes, which can be linked to its low lattice thermal conductivity [3]
.
[1] F. Brivio et al., Phys. Rev. B 2015, 92, 144308/1-8.
[2] A. M. A. Leguy et al., Phys. Chem. Chem. Phys. 2016, 18, 27051-27066. [3] A. Pisoni et al., J. Phys. Chem.
Lett. 2014, 5, 2488-2492.
81
A28: Microfabrication of an Organic TEG with vertical architecture
Matteo Massetti1,2
, Marco Cassinelli1, and Mario Caironi
1
1Italian Institute of Technology (IIT), Via Pascoli 70/3, 20133 Milan (Italy) 2Politecnico di Milano, P.zza Leonardo da Vinci 32, 20133 Milan (Italy)
E-mail: [email protected]
In recent years, the problematics linked to the reduction of fossil fuel reservoirs have pointed out the
importance of the exploitation of renewable sources of energy, especially those environmentally friendly.
Among these, thermoelectric generators (TEG) certainly occupy an important place because of their ability to
convert heat in electrical energy without any moving part and any kind of fuel, through the so-called
Seebeck effect. In the last decades, many studies were conducted on organic semiconductors (polymers,
oligomers, small molecules) towards TE applications. Moreover, these materials are interesting because
they can be integrated with traditional printing techniques, thus allowing low-cost and large-area
fabrication.
Here, we present our state-of-art regarding the fabrication of an out-of-plane TEG, using an inkjet
printing system for the deposition of the active thermoelectric materials. The resulting TEG is composed by
vertical thermocouples connected electrically in series, giving a total electrical output proportional to the
number of the legs. Then, the device power output has been measured by using our homemade system,[1]
allowing us to fully characterize its performances.
In addition, since the TEG is fabricated on a flexible substrate, its thermoelectric properties are here
discussed as a function of externally applied stresses on the structure.
Figure 1. Optical Microscope image of our vertical organic TEG final layout. The red squares correspond to the N-type legs, while the green to the P-type ones. The yellow parts are the top and bottom electrical connections.
[1] D. Beretta, M. Massetti, G. Lanzani, M. Caironi, Rev. Scien. Inst., 2017, 88 015103
82
B1: Manipulating the thermoelectric and spin properties of polymeric systems
Jonathan Ogle1, Mandefro Yehulie
2, Christoph Boehme
2, Luisa Whittaker-Brooks
1
1Department of Chemistry, University of Utah, Salt Lake City, Utah 84112 2Department of Physics, University of Utah, Salt Lake City, Utah 84112
E-mail: [email protected]
Organic semiconductors have quickly emerged as viable candidates for thermoelectric and spintronic
applications due to the distinctive advantages they offer over their inorganic counterparts such as low cost,
light weight, flexibility, and solution processability over large areas. Additionally, there are two paramount
factors that justify the serious consideration of organic semiconductors as thermoelectric materials, these are:
i) their intrinsically low thermal conductivities (<1 W m-1
K-1
) and ii) the ease of tuning their electronic
structure though molecular design, incorporation of specific structural motifs, and doping. The latter feature
also makes these systems amenable to the extraction of fundamental design principles and the establishment
of systematic structure-processing-function correlations, providing a rich tapestry for fundamental studies
of correlated transport parameters underpinning thermoelectric and spintronic applications. Polymeric
systems, in particular, PEDOT has been shown to possess high thermopowers (≈100-500 μV K-1
) due to
electron-phonon scattering in the crystalline grains and electron-phonon coupling in the counter ion
introduced to control their processability. On the other hand, the charge transport in PEDOT is typically
dominated by phonon-assisted hopping between the metallic domains within the polymer chains which turns
out to be a less effective charge transport mechanism than that observed in inorganic materials.
Consequently, the electrical conductivity and thermopower are strongly affected by the morphology,
composition, temperature, dopant levels, and orientation of this conducting polymer. Herein, we will discuss
how the various effects mentioned above affect the thermoelectric properties of PEDOT. We will also present
experimental details on an electrically detected magnetic resonance (EDMR) study of the spin dynamics in
assembled devices comprised of PEDOT thin films having different counter ions and dopant levels.
Finally, we will discuss how our findings can be used to predict and understand the thermoelectric
properties of other polymer semiconductors.
83
B2: In-situ synthesized conducting Nanocomposite - A step towards printable
polymer thermoelectrics
Rafael Abarguesa*, Pedro J. Rodríguez-Cantó
b, Alvaro Seijas
a, Eduardo Aznar
a, Clara Gómez
a, Andrés
Cantareroc, Juan P. Martínez-Pastor
a
aInstituto de Ciencia de los Materiales, Universidad de Valencia, Calle Catedrático José Beltrán 2,
46980 Paterna, Spain. bIntenanomat SL, Calle Catedrático José Beltrán 2, 46980 Paterna, Spain.
(a) Instituto de Ciencia Molecular, Universidad de Valencia, Calle Catedrático José Beltrán 2, 46980
Paterna, Spain.
E-mail: [email protected]
Conducting polymers (CPs) have received much attention due to their interesting electronic and optical
properties and potential applications in microelectronics, optoelectronics, and, of course, in thermoelectrics. The
successful application of CPs in many of the above given applications will depend on exploiting their low-cost
potential by the innovative design and development of materials for scalable and inexpensive methods to print
these CPs on flexible and rigid substrates.
Polymer nanocomposites are multicomponent materials in which a nanomaterial is dispersed inside a
polymer matrix. These materials represent an adequate solution to many present and future technological demands,
because they combine the novel properties of the nanoparticles with the unique characteristics of polymers
(mechanical properties, thin film processing, conductive/dielectric properties, low cost…). In particular, metal
nanoparticle-polymer composite materials are generating interest in many fields, such as optoelectronics and
thermoelectrics, because of the plasmonic effect exhibited by metallic nanoparticles (Au, Ag) hosted in the
nanocomposite [1]
. Thus, the combination of the excellent properties of nanomaterials and CPs is of special interest
in order to develop new multifunctional advanced materials for the fabrication of more complex devices for the
next decade.
On previous works [2,3,4]
, we reported on a novel method for the in-situ polymerization of thiophene-basedoligomers with Cu(ClO4)2 inside several host polymers to form a conducting interpenetrating polymer network (IPN). Homogeneous conducting IPN films in the order of 10
-4 to 200 S/cm were obtained
depending on the specific IPN composition. The strong advantage of this approach is to combine properties of the
host matrix with those of the in situ synthesized conducting polymers.
In this work, we report on in situ synthesis of a thiophene-based conducting polymer and Au and Ag
nanoparticles inside several host matrices by conventional coating techniques such as spincoating, Dr Blade
and by direct printing by a microplotter or inkjet printer. These novel metal-polymer nanocomposite films
show plasmonic properties and a complete tunable electrical conductivity ranging from 10-4
to 300 S/cm. First
results show promising thermoelectric properties with a Seebeck coefficient of 30.0 µC K-1 and a thermoelectric
power factor (P = S2) around 1.8 µW m-1 K-2.
Because this synthetic approach allows both for the modification of the conductivity of numerous insulating
polymers, permit the incorporation of different types of nanomaterials, and the formulation and processing
from solution as an ink, we believe that this approach can have a great impact on polymer thermoelectrics,
specially on the printing of flexible thermoelectric devices.
[1] Y. Akihito, N. Toshima. J. Electron. Mater. 2014, 43, 1492.
[2] R. Abargues, U. Nickel, P. J. Rodriguez-Canto, Nanotechnology, 2008, 19, 125302.
[3] R. Abargues, P. J. Rodríguez-Canto, R. García-Calzada, and J. Martínez-Pastor, J. Phys. Chem. C,
2012, 116, 17547.
[4] P. J. Rodríguez-Cantó, M. Martínez-Marco, J. F. Sánchez-Royo, J. P. Martínez-Pastor, R. Abargues.
Polymer, 2017, 108, 413.
84
B3: Study of Stability Mechanism of Air-Stable n-type Single-walled Carbon
Nanotube Films Doped with Benzimidazole Derivative
Yuki Nakashima1, Wenxin Huang
1, Aleksandar Staykov
2, and Tsuyohiko Fujigaya
1,2,3
1Kyushu Univ., 744 Motooka, Nishi-ku, Fukuoka, Japan 2WPI-I2CNER, 3JST-PRESTO
E-mail: [email protected]
Thermoelectric (TE) conversion is one of the most promising methods for the generation of cost-
effective electricity. TE devices have applications in many fields especially microelectronics devices due
to their simple device structures. TE generation using Seebeck effect requires both n - type and p-type TE
materials for the efficient conversion; however, deterioration of n-type nature due to air oxidation has
been the critical issue. Recently, we reported single-walled carbon nanotubes (SWCNT) sheet doped by 2-
(2-methoxyphenyl)-1,3-dimethyl-2,3-dihydro-1H- benzimidazole (o-MeO-DMBI) showed n-type property
and remarkable air-stability.[1] We chose o- MeO-DMBI because of the following reasons; i) o-MeO-
DMBI is stable under atmospheric conditions, ii) the cationic form of o-MeO-DMBI is also stable and, iii)
n-doping of the other carbon materials such as fullerene and graphene has already been reported. [2,3] Here,
we study the mechanism of the air stability of o-MeO-DMBI-doped SWCNT films by changing the doping
level (Fig. 1a).
eDIPS (Meijo Nano Carbon, EC1.5) was used as SWCNT. SWCNT films were dipped in the 0.01, 0.1, 1.0,
10 and 50 mM ethanol solutions of o-MeO-DMBI for 10 min and dried in vacuum at room temperature for
12 h. Fig.1b shows the time course of Seebeck coefficient of the SWCNT films doped with various
concentration of o-MeO-DMBI solution. It is noted that the films were kept under air condition at room
temperature to evaluate the air stability of the o-MeO-DMBI-doped SWCNT films. Positive value of Seebeck
coefficient for 0.01 and 0.1 mM doped films indicated p-type, and negative value for 1.0, 10 and 50 mM doped
films showed n-type nature of the films. Interestingly, we found that Seebeck coefficient of 1.0 mM doped film
changed to positive, while 10 mM doped film showed stable negative value. From above results, we conclude
that the mechanism of the air-stabilization of n-doping is the passivation effect by the formation of o-MeO-
DMBI layer onto the surface of SWCNT films.
Fig. 1. (a) Schematic illustration of this study and (b) Time course of Seebeck coefficient of non-doped SWCNT
Sheet and SWCNT films doped with various concentr ations of o-MeO-DMBI solutions measured at 320 K.
[1] Nakashima, Y.; Nakashima, N, Fujigaya, T. S ynth. Met. 2017. 225. 76.
[2] Bao, Z. et al. Nano Lett. 2013, 13, 1890.
[3] C heng, J.-P et al. J. Am. Chem. Soc. 2008, 130, 2501.
86
B5: Ionic thermoelectric effect and devices
Dan Zhao, Zia Ullah Khan, Simone Fabiano, Xavier Crispin
Laboratory of Organic Electronics, Department of Science and Technology, Linköping University, SE-
60174, Norrköping, Sweden
E-mail: [email protected]
Temperature is one of the most important environmental stimuli to record and amplify. While traditional thermoelectric materials are attractive for temperature/heat flow sensing applications, their sensitivity is
limited by their low Seebeck coefficient (~100 µV K-1
). Here, we take advantage of the large ionic thermoelectric Seebeck coefficient found in polymer electrolytes (~10000 µV K
-1)
[1] to introduce the concept
of ionic thermoelectric gating a low-voltage organic transistor. [2] The temperature sensing amplification of
such ionic thermoelectric-gated devices is thousands of times superior to that of a single thermoelectric leg in traditional thermopiles. This suggests that ionic thermoelectric sensors offer a way to go beyond the limitations
of traditional thermopiles and pyroelectric detectors. These findings pave the way for new infrared-gated electronic circuits with potential applications in photonics, thermography and electronic-skins.
The illustration of the thermoelectric gated transister.
[1] D. Zhao, H. Wang, Z. U. Khan, J. C. Chen b, R. Gabrielsson a, M. P. Jonsson, M. Berggren and X. Crispin, )
Energy. Environ. Sci., 2016, 9, 1450-1457.
[2] D Zhao, S Fabiano, M Berggren, X Crispin, Nat. Commun., 2017, 8, 14214
87
B6: Carbon based materials and nanocomposites for thermoelectric applications
Mario Culebras1, Maurice N. Collins
1, Eric Dalton
1, Clara M. Gómez
2 and Andrés Cantarero
2
1Stokes Laboratories, Bernal Institute, University of Limerick, Ireland
2 Molecular Science Institute, University of Valencia, PO Box 22085, 46085 Valencia, Spain
E-mail: [email protected]
During the last 10 years, thermoelectricity has become a very interesting topic in the framework of
energy harvesting [1]
. Historically, inorganic materials have dominated the thermoelectric applications. However, organic and hybrid semiconductors such as: conducting polymers and nanocomposites based on carbon materials (CNTs or graphene) are now considered the most promising candidates for the next generation of thermoelectric materials. Their thermoelectric efficiency, measured by the dimensionless figure
of merit ZT (ZT=S2σT/κ where S, σ and κ are the Seebeck coefficient, the electrical and thermal
conductivities, respectively) has been improved several orders of magnitude, with values currently very close to the inorganic materials. In addition, conducting polymers and nanocomposites based on carbon materials present several advantages over inorganic materials such as: renewable raw materials, lack of toxicity, low cost of production and etc. Single wall carbon nanotubes (SWCNTs) and double wall carbon nanotubes (DWCNTs) are widely used for producing thermoelectric nanocomposites due to their high efficiency. However, problems related with the high cost of these materials has limited their used in large scale applications. However, low cost carbon materials such as: carbon black, carbon fibers or even multi wall carbon nanotubes (MWCNTs) may be suitable for mass production in industrial processes. In particular, carbon fibers present huge potential since they are both n-type and p-type semiconductors and can be obtained from natural products such as lignin that is considered one of the most abundant components of lignocellulosic biomass
[2]. In this work we study the thermoelectric properties of carbon base material, lignin carbon
fibers, carbon black and conducting polymer nanocomposites which achieve power factor values of 155
µV/mK2.
[1] M. Culebras, C. Gomez and A. Cantarero, Materials. 2014, 7 , 6701-6732.
[2] Lignin based Carbon Fibres for Composites (LIBRE) BBI.VC1.R1-2015-2-1/720707.
88
B7: Highly Stable N-Type Carbon Nanotubes via Simple Vinyl Polymer Doping for
Flexible Thermoelectric Generators
Shohei Horike1, Tatsuya Fukushima
1, Takeshi Saito
2, Yasuko Koshiba
1 and Kenji Ishida1
1 Department of Chemical Science and Engineering, Kobe University, Kobe 657-8501, Japan 2
Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology,
Tsukuba 305-8565, Japan
E-mail: [email protected]
Converting p-type single-walled carbon nanotubes (SWCNTs) into air-stable n-type materials is an
important issue in the development of flexible thermoelectric (TE) power generators. This study reports
a series of common vinyl polymers (Fig. 1a) that can be used as nontoxic donor materials for the stable
conversion of the charge-carrier-type SWCNTs. TE charge-carrier analyses revealed that charge transfer
from the polymer dopant successfully and systematically converted SWCNTs into n- type materials, as
shown in Fig. 1a. The negative coefficients were correlated with the highest occupied molecular orbital
(HOMO) energy levels of the polymer dopants. We found that doping using polymers with ambient
HOMO energy levels, such as poly(vinyl alcohol) and poly(vinyl acetate) (PVAc), resulted in the largest
Seebeck coefficient with excellent stability exceeding three weeks. The printing and folding of these
SWCNTs on flexible substrates will be demonstrated as a specific example for implementing charge-carrier-
controlled SWCNTs in TE modules and for improving the dimensional voltage output.
Furthermore, we will describe the charge-carrier modulation of SWCNTs via PVAc doping and
dedoping under ultraviolet (UV) light irradiation to readily and precisely pair several p- and n-type
SWCNTs for use as TE elements. The Seebeck coefficient of the SWCNTs could be switched from positive
to negative by doping with PVAc. Moreover, the coefficient could be switched back to positive again
by UV-induced dedoping of PVAc (Fig. 1b). A TE module configuration and the process for producing
it will be proposed, wherein the prints and photopatterns are formed without using extra electrodes to
connect the p- and n-type elements. Our findings enable the easy, low-cost preparation of air-stable n-type
SWCNTs and fine, precise TE modules, thus permitting the exploitation of SWCNTs as flexible and eco-
friendly TE materials.
Figure 1. (a) Seebeck coefficients of SWCNTs doped with various polymers at 300 K in air. (b) Modification of
majority charge-carrier type by doping and UV-induced dedoping of PVAc. The inset shows the
photodegradation process of PVAc, in which the lack of reductive carbonyl groups results in the n- to p-type
reversion of the doped SWCNTs.
Acknowledgment This work was supported in part by a Grant-in Aid for JSPS Research Fellow (No.
17J00903).
89
B8: Enhancing the Thermoelectric Properties of Single-walled Carbon Nanotubes
by Polyelectrolytes
Motohiro Nakano1, Takuya Nakashima
1, Tsuyoshi Kawai
1 and Yoshiyuki Nonoguchi1,2
1 Gradute School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara, 630-
0192, Japan
2 JST PRESTO, Kawaguchi, Saitama, 332-0012, Japan
E-mail: [email protected], [email protected]
Flexible thermoelectric materials based on organic and nanocarbon materials have attracted great interest.
Chemical doping is an effective method to permit the optimization of thermoelectric properties. [1]
Polyelectrolytes (PEs) adsorbed on single-walled carbon nanotubes (SWNTs) is expected to modulate their
thermoelectric properties due to the specific interactions such as dipole- dipole, cation-, and CH-
interactions.[2,3] In these studies, a phenomenological insight into the improved thermoelectric properties
is still required.
Here we elucidate shallow p-doping in SWNT-PE composites, which improves the thermoelectric
performance of SWNTs.[4] The addition of PEs to SWNTs offered enhanced electrical conductivity () and
the Seebeck coefficient (), and resulted in a dramatic increase in the thermoelectric power factor (2) ≈0.5 mW/mK2 (Fig. 1). We explain the origin of enhancement of thermoelectric properties: i) shallow hole doping from weak Lewis acids to SWNTs, ii) charge compensation and stabilization induced by appropriate counter anions (Fig. 2).[5] We will also discuss the critical role for the ionic functionalities of PEs.
small anion PEs
l
arge anion
Fig. 1. Thermoelectric properties of SWNT-PE composites. Fig. 2. Schematic concept for p-doping by electrolytes.
[1] R. Kroon, D. A. Mengistie, D. Kiefer, J. Hynynen, J. D. Ryan, L. Yu and C. Müller, Chem. Soc. Rev.
2016, 45, 6147.
[2] C. K. Mai, B. Russ, S. Fronk, N. Hu, M. B. Chan-Park, J. J. Urban, R. A. Segalman, M. L. Chabinyc and
G. C. Bazan, Energy Environ. Sci. 2015, 8, 2341.
[3] M. Nakano, Y. Nonoguchi, T. Nakashima, K. Hata and T. Kawai, RSC Adv. 2016, 6, 2489.
[4] M. Nakano, T. Nakashima, T. Kawai and Y. Nonoguchi, Small 2017, 13, 1700804.[5] Y. Nonoguchi, M. Nakano, T. Murayama, H. Hagino, S. Hama, K. Miyazaki, R. Matsubara, M.
Nakamura and T. Kawai, Adv. Funct. Mater. 2016, 26, 3021.
h+
90
B9: Dual Mode Thermoelectric Transport in a Semiconducting Carbon Nanotube
Film
Yoshiyuki Nonoguchi, Chigusa Goto, Tsuyoshi Kawai
Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma 630- 0192,
Japan
E-mail: [email protected]
Semiconducting carbon nanotubes are recognized as a model enabling to study one-dimensional
thermoelectric transport and its application in flexible thermoelectric generators.1 In this context,
expanding the understanding of nanotubes’ thermoelectricity will make a significant impact on materials
science from the basics to the practical use. Here we demonstrate that a semiconducting carbon nanotube
film tailored by synthetic polymers exhibits unique thermoelectric transport reflecting a one-dimensional
band structure. Broadband absorption spectroscopy and thermoelectric measurements are utilized to assess
the purity of, and a carrier concentration in, the semiconducting carbon nanotubes. The high quality film
with no detectable one-dimensional plasmon resonance, which is closely associated with low carrier
concentration, shows the Seebeck coefficient of approximately 3 mV K-1. By supramolecular amphoteric
doping,2 the thermoelectric performance widely varies over the fifth-order conductivity range; undoped
and heavily doped films show the power factors of approximately 0.1 and 0.5 mW m-1 K-2, respectively
(Figure 1). This thermoelectric transport is explained by intrinsic and hybrid band structure models in a
one-dimensional semiconductor.
Figure 1. (a) The Seebeck coefficient and (b) power factor of semi -CNT films as a function of electrical
conductivity.
[1] Avery, A.D., Zhou, B.H., Lee, J.H., Lee, E-S, Miller, E.M., Ihly, R., Wesenberg, D., Mistry, K.S.,
Guillot, S.L., Zink, B.L., Kim, Y-H, Blackburn, J.L., Ferguson, A.J., Nature Energy 1, 16033 (2016).
[2] Nonoguchi, Y., Nakano, M., Murayama, T., Hagino, H., Hama, S., Miyazaki, K., Matsubara, R.,
Nakamura, M., Kawai, T., Adv. Funct. Mater. 26, 3021-3028 (2016).
91
B10: Ab initio modelling of thermoelectric transport in simple polymers
Roberto d’Agosta
Nano-bio Spectroscopy Group Centro Joxe Mari Korta Avenida de Tolosa, 72 E-20018 Donostia-San Sebastian, Spain
E-mail: [email protected]
We present our recent results on the calculation of the thermoelectric parameters for simple
polymers (e.g. polycarbazole) by using standard an-initio methods. We discuss some of the
conformation properties of theses polymers, the effect of negative charging, and doping with
counter-ions
92
B11: Development of n-Type Metal Nanowire/Polymer Thermoelectric
Nanocomposites with Large Power Factor
Yani Chen1, Minhong He
1, Guillermo C. Bazan
3, Jun Zhou
2 and Ziqi Liang1*
1Department of Materials Science, Fudan University, Shanghai 200433, China
2Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering,
Tongji University, Shanghai 200092, China 3Department of Chemistry and Biochemistry & Department of Materials Science, University
of California at Santa Barbara, CA 93106, USA
E-mail: [email protected]
Organic/inorganic hybrids have become the central focus of developing the next-generation
thermoelectric (TE) materials owing to a combination of their unique properties of individual components.
However, most organic-inorganic thermoelectric nanocomposites (TENCs) contain a mixture of carbon-
based nanomaterials and inorganic semiconductors. Major obstacles limiting applications of TENCs
include low power factors (PFs) and the general absence of n-type TE materials. Despite their
intrinsic high electrical conductivity and low cost, metals have been seldom reported as the inorganic
component.
In this contribution, we will report the solution fabrication of flexible n-type TENCs comprising
metallic Ni nanowires (NWs) embedded in an insulating polyvinylidene fluoride (PVDF) matrix[1]
. The
electrical conductivity and Seebeck coefficient of these TENCs are decoupled and both increase with Ni
content. The nanocomposites also exhibit typical temperature dependences of magnetic metals, such
as Ni, namely, negative in electrical conductivity, while positive in absolute Seebeck coefficient. The
resulting PF is progressively enhanced over temperature. Moreover, a remarkably low thermal conductivity
of 0.55 W m-1 K
-1 is found in these TENCs. As a result, the maximum PF of 220 μW m-1 K
-2 and the best
ZT of 0.15 are obtained at 380 K with 80 wt% Ni NWs. Recently, we further fabricated Co NWs/PVDF
TENCs via self-assembly of Co NWs in solution, which remarkably improve PF up to 520 μW m-1
K-2. This value is among the highest achieved for n-type TENCs. Intriguingly, these TENCs are
highly bendable and hard to deform, suggesting its relevance for flexible and portable TE modules.
This work offers the first demonstration that a combination of an insulating polymer and an inorganic
metal, each of which is a poor TE material, can be brought together to form a nanocomposite with
unexpectedly outstanding TE properties.
[1] Y. Chen, M. He, B. Liu, G. C. Bazan, J. Zhou, Z. Liang, Bendable n-Type Metallic Nanocomposites
with Large Thermoelectric Power Factor. Adv. Mater. 2017, 29, 1604752.
93
B12: Efficient Solution-Processed n-Type Small-Molecule Thermoelectric
Materials Achieved by Precisely Regulating Energy Level of Organic Dopants.
Dafei Yuan, Dazhen Huang, Cheng Zhang, Ye Zou, Chong-an Di, Xiaozhang Zhu*, and Daoben Zhu
Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute
of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
E-mail: [email protected]
Because of their flexibility, abundance of sources, and potential in large-area production, organic semiconducting materials are receiving increasing attention in thermoelectric generators that transform waste heat into electricity and can be used as a new type of electronic devices, such as power sensors. A working TE device should consist of both the p- and n-type modules. To date, p- type materials such as PEDOT have achieved high thermoelectric performance with high ZT values. However, the development of n-type thermoelectric materials are lagging far behind, which can be attributed to the lack of high-performance n-type organic semiconductors. To achieve high performance solution-processed n-type thermoelectric materials, doping is crucial. Designing appropriate n-type dopants is challenging for the crucial requirements of high-lying highest occupied molecular orbital (HOMO) energy level and relative
ambient stability in order to achieve high doping efficiency. We report herein the thermoelectric application
of n-type small molecule 2DQTT-o-OD[1]
that was recently developed in our group by effective n-type doping. Based on two dopants 2-Cyc- DMBI-H and (2-Cyc-DMBI)2, we synthesized a new dopant (2-Cyc-DMBI-Me)2 with methyl groups on two benzimidazoles to further increase the HOMO energy level for higher doping efficiency. These three dopants are all utilized to dope 2DQTT-o-OD and investigated the
thermoelectric properties systematically. In contrast with low power factor of 2-Cyc-DMBI-H and (2-Cyc-
DMBI)2, an unexpected high power factor of 33.3 W m-1
K-2
was achieved by the new dopant (2-Cyc-DMBI-Me)2, which, to the best of our knowledge, is the highest among solution-processed n-type small-
molecule thermoelectric materials.[2]
Figure 1 Thermoelectric performance of n-dopped 2DQTT-o-OD materials.
[1] C. Zhang, Y. Zang, F. Zhang, Y. Diao, C. R. McNeill, C.-a. Di, X. Zhu, D. Zhu, Adv. Mater. 2016, 28,
8456–8462.
[2] D. Yuan, D. Huang, C. Zhang, Y. Zou, C.-a, Di, X. Zhu, D. Zhu, ACS Appl. Mater. Interfaces 2017, 9, 28795–
28801.
94
B13: Coulomb Interactions Dominate Charge and Energy Transport in Organic
Field Effect Transistors
Hassan Abdalla1, Simone Fabiano
2, Martijn Kemerink
1
1 Complex Materials and Devices, Department of Physics, Chemistry and Biology (IFM), Linköping
University, 58183 Linköping, Sweden 2 Department of Science and Technology, Linköping University, 60174 Norrköping, Sweden
E-mail: [email protected]
The confinement of charge carriers to a quasi-2D channel in organic field effect transistors (OFETs)
dramatically increases carrier-carrier Coulomb interactions, changing the energetic landscape as perceived by
the charges. We conducted experimental and numerical (by kinetic Monte Carlo, kMC) investigations of the
thermoelectric and transport properties of single monolayer N2200 OFETs and find that the Coulomb
interaction qualitatively and quantitatively changes OFET behavior. Particularly, it causes slope changes in
and spreading of the thermopower vs. conductivity plots for different energetic disorders of the active material
(Fig.1a). In contrast, when Coulomb interactions are not considered all curves collapse to a quasi-universal
logarithmic line (Fig.1a). This confirms observations in own experiments and literature where the
thermopower vs. conductivity traces for different materials show a spread over several orders of magnitude as
well as different slopes (Fig.1b). This spread is in stark contrast to doped organic semiconductors, where a
material independent quasi-universal power-law has been observed, thus putting into question the suitability
of OFETs as a testbed for thermoelectric investigations of doped organic materials [1], [2]
.
Having direct access to the energetics of charge transport through kMC we could attribute this behavior to a
broadening and upward shift of the density of occupied states as well as an increase of carrier-carrier scattering,
being responsible for an unusual, Coulomb-induced simultaneous reduction of thermopower and conductivity.
Figure 1: Thermopower – conductivity relationship (a) calculated with kinetic Monte Carlo with full Coulomb
interactions (full symbols and solid lines) and without (open symbols and dashed lines) and (b) from own
experiments on N2200 (red symbols) and literature data of NDI3HU-DTYM2 (blue line), Pentacene (green line) and
Rubrene (brown line) taken from Refs.[2], [3].
[1] A. M. Glaudell, J. E. Cochran, S. N. Patel, and M. L. Chabinyc, Adv. Energy Mater., vol.5, no. 4, p.
1401072, Feb. 2015.
[2] F. Zhang et al., Adv. Funct. Mater., vol. 25, no. 20, pp. 3004–3012, May 2015.
[3] K. P. Pernstich, B. Rössner, and B. Batlogg, Nat. Mater., vol. 7, no. 4, pp. 321–325, Apr.2008.
95
B14: In-plane thermal conductivity of organic films using the 3ω- Volklein method
G. G. Dalkiranis1, I. Ruiz-Cózar
2, J. Ràfols-Ribé
1, M. Gonzalvez-Silveira
1, Ll. Abad
2, A. F. Lopeandía
1, J.
Rodríguez-Viejo1.
1Grupo de Nanomateriales y Microsistemas, Dep.Física, Universitat Autònoma de Barcelona,
Bellaterra, Barcelona, Spain. 2Instituto de Microelectrónica de Barcelona - Centre Nacional de Microelectrònica, Campus UAB,
Bellaterra, Barcelona, Spain.
E-mail: [email protected]
The evaluation of the figure of merit of thermoelectric materials often requires independent evaluations of
the electrical conductivity, the Seebeck coefficient and the thermal conductivity. Reliable measurements of
this last parameter, specially the in-plane component of organic films, remain very challenging due to
the lack of appropriate experimental techniques. We have recently developed a modification of the 3ω–
Volklein technique that can be used to measure with very high sensitivity the in-plane thermal conductance
of thin film organic layers up to temperatures close to their glass transition temperature. Here we show the
principle of the methodology and its application to measure the in-plane thermal conductivity of small
molecule and polymeric thin films. We anticipate that the described methodology may provide a suitable and
efficient approach to determine the in-plane thermal conductivity of both vapor-deposited or solution-
processed organic materials.
96
B15: Molten Carbonate Electrolyte Based Thermocells for High Temperature
Waste Heat Recovery
Sathiyaraj Kandhasamy1, Signe Kjelstrup
2, Asbjørn Solheim
3 and Geir Martin Haarberg
1
1Department of Materials Science and Engineering, Norwegian University of Science and Technology
(NTNU), Trondheim, Norway 2PoreLab, Department of Chemistry, NTNU, Trondheim, Norway 3SINTEF Materials and Chemistry, SINTEF, Trondheim, Norway
E-mail: [email protected]
A thermocell with molten carbonate electrolyte mixture with two identical gas (CO2|O2) electrodes shows
the possibility to utilize waste heat as a power source. The use of ion-conducting molten carbonate electrolyte
with two identical and reversible gas (CO2|O2) electrodes in the thermocell gives a high Seebeck coefficient (~
1 mV/K).[1,2]
Also, it has the advantage to harvest the industrial waste heat at high temperatures and utilize the
available CO2 rich off-gases from metal producing industries.
The inclusion of solid oxide in the electrolyte mixture was found to influence the transported entropy of the
carbonate ions and expand the appropriate conditions for thermoelectric conversion. As well as the addition of
solid oxide to the molten carbonate melt alters also the system’s Seebeck coefficient. [1]
Here the change in
Seebeck coefficient and power conversion efficiency of the molten carbonate thermocell due to compositional
change with various selected solid oxides was studied. The stability of different dispersed solid oxides in the
molten carbonate melt was also studied.
(A) (B)
Figure (A) Cross-sectional view of the thermocell used and (B) Thermocells Seebeck coefficient with electrolyte mixture
of different solid oxides dispersed in 45 vol% of eutectic (Li, Na)2CO
3 melt.
[1] M. T. Børset, X. Kang, O.S. Burheim, G.M. Haarberg, Q. Xu and S. Kjelstrup, Electrochim. Acta,
2015, 182, 699.
[2] S. Kandhasamy, L. Calandrino, O. S. Burheim, A. Solheim, S. Kjelstrup and G. M. Haarberg, J.
Electrochem. Soc., 2017, 164, H5271.
97
B16: Recent Progress on Understanding the Origin of Giant Seebeck Effect in
Organic Small Molecules
Hirotaka Kojima1, Ryo Abe
1, Takanobu Takeuchi
1, Satoshi Inoue
1, Seiichiro Izawa
2, Mitsuru Kikuchi
2,
Masahiro Hiramoto2, Yumi Yakiyama
3, Hidehiro Sakurai
3, Masakazu Nakamura
1,2
1Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-
cho, Ikoma, Nara 630-0192, Japan 2Institute for Molecular Science, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
3Department of Applied Chemistry, Osaka University, Suita, Osaka 565-0871, Japan
E-mail: [email protected]
We recently reported extraordinary large Seebeck coefficients around 100 mV/K which appear in several
thin films of organic thermoelectric (TE) materials [1]
. Their temperature dependences are summarized in
Fig. 1. The hatched area denotes a range of the - curve predicted by the conventional theory. As indicated in this figure, almost all of the materials tested exhibit much larger Seebeck coefficient than the upper limit of the conventional theory. Up to now, origin of the giant Seebeck effect (GSE) has not been elucidated yet. In this conference, we will present the results of resent experimental and theoretical works and discuss the possible origin of GSE.
TE measurements for organic single crystals were performed to avoid the influence of grain boundaries and
defects. As a result, a rubrene single crystal (Fig. 2) exhibited large negative Seebeck coefficients, up to –15
mV/K. This result indicates that the GSE is an intrinsic property of organic semiconductors. For much
broader survey works, a new measurement system specialized for powdery samples has been developed.
Powder of an organic semiconductor is put into an insulating sleeve and pressed by two heated conducting
rods which are connected to electrical measurement systems. This technique enables us to measure TE
properties of any non-sublimable or insoluble materials.
In addition to these experimental works, MD calculations have been also performed to estimate thermal
conductivities of organic solids. C60 showed small because of their free rotation even in a crystalline state. The anisotropic was obtained for sumanene crystals and in the stacking direction was as small as that of
C60 (Fig. 3). Such small along conduction direction may play an important role to emerge GSE. Other calculations based on DFT theory were also performed for the analyses of vibronic coupling in the molecules.
[1] M. Nakamura et al. ICOT 2016, OA16.; M. Nakamura, H. Kojima, Chemistry 71, 31 (2016) (in Japanese).
98
B17: Low-temperature characteristics of a thermoelectric generator using organic
charge-transfer salts
Yasuhiro Kiyota, Tadashi Kawamoto and Takehiko Mori
Department of Material Science and Engineering, Tokyo Institute of Technology, 2-12-1 O- okayama, Meguro-ku, Tokyo 152-8552 Japan. E-mail: [email protected]
Recently organic charge-transfer salts have been investigated as thermoelectric materials.[1,2] A
representative organic conductor (TTF)(TCNQ) is a candidate of organic thermoelectric material; the power
factor of single-crystal (TTF)(TCNQ) is 39 μW m-1 K-2.[3] The value is not so large but organic charge-transfer
salts are important because of the n-type thermoelectric properties. In particular, we have paid attention to
the giant power factor of Cu(DMDCNQI)2 at low temperatures.[1,4] In the present work, we have prepared a
single-junction thermoelectric generator (TEG) using organic charge-transfer salts and investigated the
thermoelectric properties at low temperatures.
Figure 1a shows an illustration of the TEG. Two single crystals were linked at the hot side whereas
electrically isolated at the cold side. Single crystals of (BTBT)2PF6 and (TMTSF)2PF6 were used as p- type
thermoelectric materials,[5-7] whereas Cu(DMDCNQI)2 was used as the n-type material. We measured the
resistivity, thermopower, S, and power output characteristics at low temperatures.
Four-probe resistivity of (BTBT)2PF6 and (TMTSF)2PF6 shows metallic behavior down to 150 K. Four-
probe resistivity of Cu(DMDCNQI)2 is metallic down to 4.2 K. Two-probe resistivity decreases around room
temperature, but shows an upturn around 200 K. Figure 1b shows temperature dependence of S. S of these
crystals decreases with lowering the temperature in consistent with the metallic behavior. However, S of
Cu(DMDCNQI)2 gradually increases below 150 K, suggesting a large PF at low temperatures. S of the TEG
is given by a sum of S in (TMTSF)2PF6 and Cu(DMDCNQI)2. Figure 1c shows temperature dependence of
resistance, generated voltage, and power output of the TEG when 10 K temperature gradient is applied.
Power output is influenced by the reduction of generated voltage rather than resistance. Therefore, maximum
power output 4 nW is observed at room temperature.
Figure 1 (a) An illustration of the TEG. (b) Temperature dependence of thermopower in (TMTSF)2PF6, Cu(DMDCNQI)2, and the
TEG. (c) Temperature dependence of resistance, generated voltage, and power output in the (TMTSF)2PF6 – Cu(DMDCNQI)2
TEG when 10 K temperature gradient is applied.
[1] F. Huewe et al., Adv. Mater. 29, 1605682 (2017).
[2] K. Pudzs et al., Adv. Elctr. Mater. 3, 1600429 (2017).
[3] P. M. Chaikin et al., Phys Rev. B 13, 1627 (1976).
[4] T. Mori et al., Phys Rev. B 38, 5913 (1988).
[5] T. Kadoya et al., Phys. Chem. Chem. Phys. 15 17818 (2013).
[6] Y. Kiyota et al., J. Am. Chem. Soc. 138, 3920 (2016).
[7] K. Bechgaard et al., Solid State Commun. 33, 1119 (1980)
99
B18: Print Layout Design for Roll-to-Roll Produced Thermoelectric Generators
Andres Rösch, André Gall, Matthias Hecht, Silas Aslan, Frederick Lessmann, Verena Schendel, Uli Lemmer
Light Technology Institute, Karlsruhe Institute of Technology (KIT) Engesserstrasse 13, 76131
Karlsruhe E-mail: [email protected]
We present a design where thermocouples consisting of solution processable semiconductors are printed in a 2D pattern on a thin substrate foil using a roll-to-roll process. With a and fully automated folding process this pattern is folded into the third dimension arranging the thermocouples vertically and thereby forming a sugar cube sized generator.
Thermal and electrical properties of the generator can be adapted very easily by altering the print layout. By setting the dimensions and position of the thermocouples correctly the thermal impedance can be matched to the heat source and heat sink. The electrical impedance can be matched to the load in the same fashion. Inaccuracies and unwanted effects of the printing process can equally be compensated within the layout.
Such mechanically flexible generators can be made fit to nearly any form of heat source such as cylindric heat pipes
or other non-planar surfaces. Our approach allows applications ranging from powering wireless energy self-sufficient low-
power sensor or actuator systems for industrial use to wearables.
100
B19: Organic Solar Thermoelectric Generators
José Piers Jurado1
, Osnat Zapata-Arteaga1, Bernhard Dörling
1 and Mariano Campoy-Quiles
1
1Materials Science Institute of Barcelona (ICMAB-CSIC), Campus of the UAB, 08193 Bellaterra,
Spain
E-mail: [email protected]
Solar Organic Thermoelectric Generators (SOTEG) are solid state devices that directly convert sunlight
into electrical energy through the Seebeck effect. SOTEGs are an emerging technology that have the
potential to become complementary to Photovoltaics (PV) because they can harvest the sun’s energy in the
infrared region (heat), something PV cannot do.
In this work, we develop a custom-made experimental set-up to measure the Seebeck coefficient and
electrical conductivity of thermoelectric samples exposed to light, providing preliminary insight into the
ability of the sun as a source of heat to drive SOTEGs. Results are discussed in terms of convection effects
and light concentration. In addition, we use Fourier- Transform Infrared Spectroscopy (FTIR) to
characterize the absorption in the IR range of organic thermoelectric samples. Interestingly, many of the
commonly used doped organic thermoelectrics exhibit a pronounced absorption in the near IR, which
implies that the same material can act simultaneously as a light absorber and a thermoelectric material.
We present results for several commercially available, Carbon Nanotubes (CNTs) with different
chirality and length, and for the polymers Poly(3-hexlthiophene) (P3HT), and poly(3,4-
ethylenedioxythiophene) polystyrene sulfonate (PEDOTT:PSS). We further compare the performance of
pristine films of these thermoelectric materials with that of doped films and composites.
101
B20: Modulation of thermoelectric of PEDOT/PSS by carrier injection with
ferroelectrics
Masahiro Ito1, Kazuya Okamoto
2, Takashi Nakajima
3, Hiroaki Anno
2, Takahiro Yamamoto
1
1Department of Liberal Arts (Physics), Tokyo University of Science, Tokyo, Japan 2Department of
Electrical Engineering, Tokyo University of Science, Yamaguchi, Yamaguchi, Japan 3Department of Applied Physics, Tokyo University of Science, Tokyo, Japan
E-mail: [email protected]
PEDOT/PSS is expected to be a potential candidate for flexible organic thermoelectric materials. Thermoelectric performance of PEDOT/PSS is known to be enhanced by incorporating with Bi2Te3
[1]or
carbon nanotubes[2]
, or a modification of a dopant. [3]
In addition, the thermoelectric properties of PEDOT/PSS can also be modulated by a carrier injection using field effect transistor (FET).
[4]In this study, instead of such
a FET technique, we propose a new technique of carrier injection using the spontaneous polarization of ferroelectric materials such as vinylidene fluoride/trifluoroethylene (VDF/TrFE) copolymer. The new technique without power consumption is appropriate for the application of thermoelectric energy harvesting.
In this work, we prepared PEDOT/PSS-VDF/TrFE hybrid samples in the following procedure.
PEDOT/PSS (Clevious PH1000) and 5 wt% dimethyl sulfoxide were mixed by stirring. The solution was
then spin-coated onto a glass substrate. After Au was deposited as the source and drain electrodes, the
VDF/TrFE solution was spin-coated. Finally, Al was deposited as the gate electrode. The thicknesses of
PEDOT/PSS and VDF/TrFE were 40 nm and 600 nm, respectively. The Seebeck coefficient and electric
conductivity were measured using ZEM-3 (Advance Riko, Inc.).
Figure 1 shows the temperature dependencies of the Seebeck coefficient for the PEDOT/PSS with (i) pristine
VDF/TrFE, i.e., without spontaneous polarization, (ii) positively polarized VDF/TrFE, and (iii) negatively
polarized VDF/TrFE. For (i) and (iii), the Seebeck coefficients were 20 μV/K, which were consistent with
the results obtained in standard PEDOT/PSS, and electric conductivities also coincided. (We should verify
condition of hole injection such as carrier density.) On the other hand, the Seebeck coefficients increased and
electric conductivities decreased by the electron injection for (ii). Consequently, the power factor increased
by 10%, when electrons were injected.
Our experiment demonstrated that the Seebeck coefficient and the power factor was successfully
enhanced by the carrier injection method using the spontaneous polarization of VDF/TrFE. We thus expect
that thermoelectric performance will be further improved if the optimal amount of carriers is injected.
Figure.1. Average temperature dependencies of the Seebeck coefficient for PEDOT/PSS-VDF/TrFE hybrid structure.
[1] B. Zhang, J. Sun, H.E. Katz, F. Fang, R.L. Opila, Appl. Mater. Interfaces, 2010, 2, 3170.
[2] G. P. Moriarty, K. Briggs, B. Stevens, C. Yu, J. C. Grunlan , Energy Technol., 2013, 1, 265.
[3] O. Bubnova, Z.U. Khan, A. Malti, S. Braun, M. Fahlman, M. Berggren, X. Crispin, Nature Mater. 2011, 10,
429.
[4] O. Bubnova M. Berggren, X. Crispin, J. Am. Chem. Soc. 2012, 134, 16456
102
B21: In-plane Thermoelectric Properties of Hybrid Films Consisting of a Nano
Titanium Disulfide, Conducting Polymer PEDOT−PSS, and Carbon Nanotubes
Hiroaki Anno and Kazuya Okamoto
Department of Electrical Engineering, Tokyo University of Science, Yamaguchi (TUSY) 1-1-1
Daigakudori, Sanyo Onoda, Yamaguchi 756-0884, Japan
E-mail: [email protected]
Hybrid films consisting of a nano titanium disulfide (nano-TiS2), poly(3,4- ethylenedioxythiophene)-
poly(styrenesulfonate) (PEDOT−PSS), and carbon nanotubes (CNT’s) were prepared by a drop-casting
method and their in-plane thermoelectric properties were investigated. PEDOT−PSS was used as a binder of
CNT network to improve the electrical conductivity of the hybrid films. Nano-TiS2 particles were dispersed
in the hybrid films to reduce the thermal conductivity by increasing the phonon scattering at interfaces
between nano-TiS2, PEDOT−PSS, and CNT.
Nano-TiS2 particles, disc-shaped with an average diameter of 223±57.9 nm and a thickness of about
14.6±5.9 nm, were synthesized by a process similar to the literature.[1]
A mixture of PEDOT−PSS (PH-
1000, Heraeus) solution and 5vol.% dimethyl sulfoxide (DMSO, Sigma-Aldrich) was stirred for 1h. Nano-
TiS2 particles and CNT (the super-growth method, Zeon Corporation) were added to the
PEDOT−PSS/DMSO solution and dispersed by sonication. The weight ratio of nano-
TiS2:PEDOT−PSS:CNT was 1:9:x, where x = 1−90. The prepared solution was cast on a polyimide
substrate and dried at 60 °C in air for about 12 h to form a hybrid film. The in-plane Seebeck coefficient (S//)
and electrical conductivity (σ//) were measured by a ZEM3 system (ADVANCE RIKO, Inc.), and the in-
plane thermal conductivity (κ//) was evaluated by an AC calorimetric method.
Table 1 compares the room temperature thermoelectric properties for the hybrid film with x = 23
(CNT content = 70 wt%) with those for PEDOT−PSS and CNT buckypaper (CNT BP). From the
dependences of S// and σ// on CNT content for the hybrid films, S// monotonically increased to about 33
µVK−1
as the CNT content increased, reflecting high S// of CNT. On the other hand, σ// for the hybrid films
was almost constant at 350−400 Scm−1
, which is greater than that for CNT BP, due to the contribution of
high σ// of PEDOT−PSS. κ// for the hybrid film decreased to 0.91 Wm−1
K−1
, which is less than that for
PEDOT−PSS and CNT BP. It can be considered that the phonon scattering is enhanced in the hybrid film
by an increased density of interfaces due to the nano-TiS2 dispersion in CNT network covered with
PEDOT–PSS. Moreover, the decrease in orientation of CNT network due to the dispersion of TiS2 may
contribute to preventing effectively thermal conduction between CNT’s. Due to the significant decrease in
κ//, the in-plane thermoelectric figure of merit ZT// = 0.0163 for the hybrid film was about 4 times greater
than that for PEDOT−PSS and CNT BP.
Table 1. In-plane thermoelectric properties of nano-TiS2/PEDOT−PSS/CNT and reference materials
Material σ// (Scm−1
) S// (µVK−1
) κ// (Wm−1
K−1
) ZT//
Nano-TiS2/PEDOT−PSS/CNT 406 33.3 0.91 0.0163
PEDOT−PSS 746 16.2 1.43 0.0045
CNT BP 291 46.1 5.95 0.0034
This article is based on results obtained from a project commissioned by the New Energy and Industrial
Technology Development Organization (NEDO). The authors would like to thank Zeon Corporation for joint
research and support. The authors would also like to thank Ph. D. Y. Hirano, graduate student K. Oshima,
and K. Goto from TUSY, for assisting with the experiments. The authors would like to thank Prof. Emer. N.
Toshima and Prof. Y. Shiraishi from TUSY, for useful discussions.
[1] S. Jeong, D. Yoo, J.-T. Jang, M. Kim and J. Cheon, J. Am. Chem. Soc., 2012, 134, 18233−18236.
103
B22: Flexible thermoelectric device based on ALD-grown ZnO and ZnO:benzene
thin films
Marin Giovanni, Karppinen Maarit
Aalto Univeristy, School of Chemical Engineering, Kemistintie 1, 01250 ESPOO
E-mail: [email protected]
The flexible device is fabricated on a plastic substrate (Polyethylen Naphthalate, PEN) with electrical contracts being evaporated Copper. The thermoelectric ZnO is deposited by ALD into the needed pattern
(Figure 1) with masking tape. ZnO:benzene hybrid superlattices[1]
are on Si wafers because the necessary
deposition temperature is not compatible with the PEN substrate.
In the research we analyze the dependency of the electrical response to a temperature gradient applied
between top and bottom surfaces of the devices. The thickness of the ZnO is varied (in different devices)
between 100 and 500 nm and all are then tested with the same temperature cycling (from 30°C to 100°C and
back to 30°C). The device’s response is measured with an open circuit as well as a circuit with a defined load (1.2
Ω) to obtain the open circuit voltage as well as the voltage under load.
Figure 1: Photo of the thermoelectric device on the transparent PEN. The thickness of the ZnO layer is around 300nm with
some non-uniformity due to the masking tape present during the deposition. On the bottom-right corner a zoomed picture
of a single pad is shown. The design is easily scalable to smaller or bigger pad dimensions.
[1] T. Tynell, I. Terasaki, H. Yamauchi, and M. Karppinen, “Thermoelectric characteristics of
(Zn,Al)O/hydroquinone superlattices,” J. Mater. Chem. A, vol. 1, no. 43, pp. 13619–13624, 2013.
104
B23: Development of Thin Film Organic TE Generator based on
tetrathiotetracene
Martins Rutkis1, Kaspars Pudzs
1, Aivars Vembris
1, Simon Woodward
2
1Institute of Solid State Physics, University of Latvia, Ķengaraga 8, Riga, LV-1063
2GSK Carbon Neutral Laboratory for Sustainable Chemistry, University of Nottingham, Jubilee
Campus, Nottingham, NG7 2GG, United Kingdom
E-mail: [email protected]
To solve a problem growing emission of CO2 major attention is paid to replace fossil resources by
“green” energy production based on renewable sources. At same time it is estimated that mankind loses as
low level heat (<200 °C) are approximately 20% of total power consumption. This globally lost amount
is greater than the total annual energy usage of all EU member states. It is obvious that direct conversion
of this wasted energy in to electrical power by means of devices exploiting thermo- electrical (TE) effect
will have huge impact on energy production. Wider usage of such TE convertors for harvesting of
waste energy is limited by cost and availability of TE active materials. Therefore within a last decade
huge attention of research community is paid for search of low-cost and effective TE materials. Organic
materials attract increasing attention due to the advantages of mechanical flexibility and low-cost
synthesis. Within this contribution a proof of concept device of planar thin film TE generator based on
organic materials is built and its power generation characterized. Thin films of p- and n- type organic
semiconductors for thermo-electrical (TE) applications are produced by doping of tetrathiotetracene
(TTT). To obtain p-type material TTT is doped with iodine during vacuum deposition of thin films or by
post-deposition doping using controlled exposure to iodine vapors. Thermal co- deposition in vacuum of
TTT and TCNQ is used to prepare n-type thin films. The attained thin films are characterized by
measurements of Seebeck coefficient and electrical conductivity. Seebeck coefficient and conductivity
could be varied by altering the doping level. P-type TTT:iodide thin films with a power factor of 0.52 μW m-
1 K
-2, electrical conductivity of 130 S m
-1 and Seebeck coefficient of 63 μV K-1 and n-type TCNQ:TTT
films with power factor of 0.33 μWm-1
K-2
, electrical conductivity of 57 S m-1 and Seebeck coefficient of
-75 μV K-1 are produced. Engineered deposition of both p- and n-type thermoelectric conducting
elements on the same substrate to form TE generator is demonstrated.
Figure 1. Chemical structures of tetrathiotetracene (TTT) and tetracyanoquinodimethane (TCNQ).
105
B24: Thermoelectrical Properties of 2- and 2,8-Substituted Tetrathiotetracenes
thin films
Kaspars Pudzs1, Martins Rutkis
1, Janis Uzulis
1, Aivars Vembris
1, Simon Woodward
2
1 Institute for Solid State Physics, University of Latvia, 8 Kengaraga Street, LV-1063 Riga,
Latvia 2GSK Carbon Neutral Laboratories for Sustainable Chemistry, Jubilee Campus, University of
Nottingham, Nottingham NG7 2TU, United Kingdom
E-mail: [email protected]
Humankind is facing a serious increasing demand for energy. With the decrease in fossil fuels,
renewable energy sources will be essential for resolving the power crisis in the future. Thermoelectric
devices are used for the direct conversion of heat to electricity. In principle, these devices can use any
thermal source including solar and waste heat. Therefore, thermoelectric materials play a key role in the
development of sustainable energy-efficient technologies.
Radical ion salts from the oxidation of the electron-rich acene tetrathiotetracenes (TTTs) are potentially
of wide use in synthetic organic metals and thermoelectric devices due to their ability to form quasicrystalline
one dimensional electrical conductors.
Chemical structures of studied 2,8-R1, R
2-substituted tetrathiotetracenes.
In this work we report studies of vacuum deposited thin films of TTT derivatives. It shows final electrical
conductivities, σ (in plane) from 1.02 × 10-5 S cm
-1 di(MeO)TTT to 3.74 × 10-4 S cm
-1 MeTTT. A associated
range of Seebeck coefficients from 230-870 μVK-1 (vs. 855 μV K
-1 for TTT) was also determined. Well
defined micro crystallites showing blade, needle or mossy like habits are observed by scanning electron
microscopy. Doping of TTT derivatives with iodine produces optimal p-type behaviour where: electrical
conductivity in plane is 6.44×10-3 Scm
-1 and Seebeck coefficient 175 μVK-1
.
Acknowledgement: This work has been supported by ERAF project Nr. 1.1.1.1/16/A/046
106
B25: Enhanced Thermoelectric Performance of Copper Phthalocyanine by Iodine
Doping
Yanling Chena, Sanyin Qu
a*, Qin Yao
a, Lidong Chen
a*
aState Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai
Institute of Ceramics, Chinese Academy of Science, Shanghai 200050, China.
E-mail: [email protected]
Metal phthalocyanine compounds are considered as the potential thermoelectric material because of their
good heat stability and chemical stability. But their poor electrical transport properties greatly impede the
applied research. Chemical doping is an efficient method to control and optimize the electrical transport
properties of organic semiconductors, which have a great influence on thermoelectric properties of metal
phthalocyanine compound.
In this work, we systematically studied the effect of iodine doping on the thermoelectric properties of
copper phthalocyanine (CuPc). A series of CuPcIx (x=0, 0.5, 0.75, 1.0, 1.25, 1.5 and 1.75) were prepared by
heating in an iodine ambient at 400 K. The microstructure and charge transport of the CuPcIx was
characterized by XRD, SEM, XPS, Raman and UV-Vis. The results suggested that the iodine doping not
only increased the carrier concentration, but also enhanced the carrier mobility by shortened the
intermolecular distance between the two adjacent phthalocyanine rings of CuPc, which enhanced electronic
cloud overlaps along the stack direction. Therefore, the electrical conductivity of CuPcIx was significantly
increased. The highest electrical conductivity was up to 914 Sm-1
, increased by about 11 orders of
magnitude compared to the undoped sample, and the maximum power factor of 2.73 μWm-1
K-2
was obtained
in CuPcI1.5.
[1] Inabe T, Tajima H. Phthalocyanines versatile components of molecular J. Chemical reviews, 2004,
104(11): 5503-5534.
[2] Craciun M F, Rogge S, den Boer M J L, et al. Electronic Transport through Electron‐Doped
Metal Phthalocyanine Materials[J]. Advanced Materials, 2006, 18(3): 320-324.
[3] Krull C, Robles R, Mugarza A, et al. Site-and orbital-dependent charge donation and spin manipulation
in electron-doped metal phthalocyanines[J]. Nature materials, 2013, 12(4): 337-343.
[4] Nakamura S, Amatatsu H, Ozaki T, et al. Electrical Properties of Bromine-Doped Nickel
(Phthalocyanine) Films and Their Structural Change[J]. Japanese journal of applied physics, 1988,
27(5R): 830.
107
B26: Conducting polymers: Opening new avenues in room temperature
thermoelectric applications
Meetu Bharti1,2
, Ajay Singh1, K. P. Muthe
1, S. C. Gadkari
1, D. K. Aswal
1,3
1Technical Physics Division, Bhabha Atomic Research Centre, Mumbai-400094, INDIA
2All India Jat Heroes’ Memorial College, Rohtak-124001, INDIA 3CSIR National Physical Laboratory, New Delhi 110011, INDIA
E-mail: [email protected]
Conducting polymers offer various advantages over inorganic thermoelectric materials such as eco-
friendliness, a reduced manufacturing cost, flexibility, low thermal conductivity and amenability to
tuning of electrical properties through doping; have recently drawn much attention for development of
thermoelectric devices for low temperature heat (≤ 150 °C) recovery programmes1-4. To have practical
applications on curved hot surfaces, we synthesized conducting polymers based films on flexible
substrates using drop-casting method and photo-polymerization route. Hybrid films of polypyrrole and
silver (PPy-Ag) revealed an interesting property that inspite of adding high thermally conducting Ag
particles overall thermal conductivity of composites curtailed down. This synergetic combination of high
electrical conductivity, extremely low thermal conductivity along with moderate Seebeck coefficient in
the PPy-Ag films resulted in the highest figure-of-merit of ~ 7.4×10-3 at 335K among reported PPy
based materials. Whereas, in case of polymer PEDOT:PSS we observed significant improvement in
electrical conductivity (from 1.5 S/cm to 150-250 S/cm) when treated with organic solvents such as
DMSO/EG. Irrespective of tunable electrical conductivity, Seebeck coefficient for all the samples was
observed nearly same and resulted in much improved power factor. A flexible thermoelectric
generator consisting of array of thirty elements was fabricated by drop-casting DMSO mixed
PEDOT:PSS solution through patterned mask. This thermoelectric array generates an output voltage of
~ 18 mV under a temperature gradient of 80K. In summary, the lightweight, flexible, non- toxic
polymeric films prepared by a simple nature-friendly process have exhibited their potential for
thermoelectric power generation near room temperature.
[1] M. He, F. Qiu, Z. Lin, Energy Environ. Sci. 2013, 6, 1352.
[2] O. Bubnova, X. Crispin, Energy Environ. Sci. 2012, 5, 9345.
[3] G-H. Kim, L. Shao, K. Zhang, K. P. Pipe, Nat. Mater. 2013, 12, 719
[4] M. Bharti, A. Singh, S. Samanta, D.K. Aswal, Prog. Mater. Sci. 2017,
https://doi.org/10.1016/j.pmatsci.2017.09.004
108
B27: Study the thermoelectric properties under photoexcitation base on the
CH3NH3PbI3 polycrystalline thin films
Ling Xu a,*， Ping Wu
a, Yan Xiong
a
a Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan
430074, China
Electronic mail: [email protected](L.Xu)
This article reports using photoexcitation-generated excited states to adjust CH3NH3PbI3
polycrystalline thin film’s thermoelectric properties, we found that photoexcitation can
simultaneously increase its Seebeck coefficient and electrical conductivity with multilayer
electrode/polymer/electrode thin-film design. Our experimental results show that photoexcitation can
increase the Seebeck coefficient from 26 μV/K to 17 mV/K with increasing light intensity from 0%
to 100%. Simultaneously, the electrical conductivity is also increased from7.8×10-6
S/m in the dark
to 4×10-5
S/m in illumination condition. The Power Factor (PF) value of 11.51 nW/mK2 in the
excited state is further bigger than the PF of 5.27×10-6
nW/mK2 in the dark condition. We know
traditional doping leads to increased electrical conductivity but decreased Seebeck coefficient, which
limits the enhancement of power factor. In the CH3NH3PbI3，the excitons generated by the
photoexcitation in the perovskite film can be easily converted into free electrons and holes to
increase the carrier concentration, then enhancing the electrical conductivity. In addition, we found
that the photoexcitation can effectively restrain the Seebeck coefficient reduction for the phase
structure change. As a result, our experiment further demonstrate that an photoexcitation can used as
an effective way to simultaneously develop high Seebeck coefficient and electrical conductivity
through excited states in an organic semiconducting meterials with multilayer
electrode/polymer/electrode thin-film devices. Simultaneously, it is also develop and enhance
organic-inorganic hybrid peorvskite thermoelectric properties as some contribution.
Key words:CH3NH3PbI3 polycrystalline thin-films; photoexcitation generate excited state; Seebeck
coefficient; electrical conductivity
109
B28: Synthesis of n-type nickel-tetrathiooxalate polymer with improved and
reproducible thermoelectric characteristics
Roman Tkachov1,2
, Lukas Stepien2, Robert Grafe
2, Olga Guskova
3, Anton Kiriy
3, Heiko Reith
4, Christoph
Leyens1
1Technische Universität Dresden, Helmholtzstraße 7, 01062, Dresden, Germany
2Fraunhofer Institute
for Material and Beam Technology IWS, Winterbergstraße 28, 01277, Dresden, Germany 3Leibniz Institute of Polymer Research Dresden, Hohe Straße 6, 01069, Dresden, Germany
4Leibniz-Institute for Solid State and Materials Research, Helmholtzstraße 20, 01069, Dresden,
Germany E-mail: [email protected]
The problem of the shortage of n-type polymers caused considerable interest in the recent years,
especially to one of the most promising coordination polymers – poly[Kx(Ni-ett)].[1]
Despite significant
progress made in obtaining material with a high thermoelectric performance, the structure of the polymer
has not yet been clearly revealed. We have established that the process of partial
oxidation, which is necessary for the polymerization step, can be done in advance at the stage of the
monomer’s synthesis.[2]
Preliminary oxidative decarbonylation of the 1,3,4,6-tetrathiapentalene-2,5- dione
(TPD) leads to the potassium tetrathiooxalate (K2tto). In contrast to the TPD, which was previously used in
this reaction as a pre-monomer, K2tto is actually a true monomer unit and does not require any additional
transformations to form a monomeric unit. In this case, this results in poly(Ni- tto), which has not only
improved reproducibility and thermoelectric characteristics, but is also more stable under ambient
conditions.
Additionally we consider a possibility to prepare a printable paste based on this coordination poly- mer.
In order to avoid losses in thermoelectrical performance and in contrast to the generally accepted procedure
for the preparation of pastes based on composite materials,[3]
we obtained a paste without any supporting
additives with isolating nature. The paste was successfully used in the printing process; a flexible full-
organic thermoelectric generator was printed and tested under ambient conditions.
Figure 1. TPD and K2tto in the synthesis of poly[Kx(Ni-ett)] and poly(Ni-tto)
[1] Y. Sun, L. Qiu, L. Tang, H. Geng, H. Wang, F. Zhang, D. Huang, W. Xu, P. Yue, Y. Guan, F. Jiao,
Y. Sun, D. Tang, C. Di, Y. Yi, D. Zhu, Adv. Mater., 2016, 28, 3351–3358.
[2] R. Tkachov, L. Stepien, A. Roch, H. Komber, F. Hennersdorf, J. J. Weigand, I. Bauer, A. Kiriy, C.
Leyens, Tetrahedron, 2017, 73, 2250-2254.
[3] A. K. Menon, E. Uzunlar, R. M. W. Wolfe, J. R. Reynolds, S. R. Marder, S. K. Yee, J. Appl. Polym.
Sci., 2017, 134, 6829.
POSTERS
113
P1: 5,5’-Diazaisoindigo: an Electron-Deficient Building Block for Donor–
Acceptor Conjugated Polymers
Yang Lu, Jie-Yu Wang*, Jian Pei
*
Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education,
College of Chemistry and Molecular Engineering, Peking University, 100871 Beijing, China
E-mail: [email protected]
Recently, we develop a facile method to synthesize a novel electron-accepting unit, 5,5’- diazaisoindigo
(5DNIID-Br2), in good yield. DFT calculations suggested that 5DNIID has a lower LUMO level than 7DNIID. Moreover, compared to 7DNIID, the two sp2 nitrogen atoms in 5DNIID would not be occluded
after introducing alkyl side chains, which is beneficial to the formation of intermolecular N···H hydrogen
bonds and N···S interactions, leading to an ordered molecular arrangement and thus enhanced device
performance.
In conclusion, we reported a facile synthesis of a new isoindigo derivative, 5DNIID-Br2, and further explored its application as an electron acceptor unit in D–A conjugated polymers. CV measurement of
5DNIID-Br2 showed an ultra-low LUMO level of -3.92 eV owing to the introduction of two electron- deficient nitrogen atoms in the para-position of the amine groups in the isoindigo π skeleton, which was also
0.08 eV lower than that of the 7DNIID analogue. The different positions of nitrogen atoms exhibited significant effects on the photophysical and electrochemical properties of the two analogues. Moreover, an
unusual polymerization condition was applied to afford the D–A conjugated polymer 5DNIID-2T, which
showed typical p-type transport characteristic with hole mobilities of up to 1.27×10-3 cm2 V-1 s-1 under air. Our research provides a reliable approach to synthesize 5,5’-diazaisoindigo and its derivative, which could be an
electron-deficient building block for high-performance organic semiconductors.
Figure 1. Molecular structures of IID, 7DNIID and 5DNIID.
[1] Y. Lu, Y. Liu, Y.-Z. Dai, C.-Y. Yang, H.-I. Un, S. W. Liu, K. Shi, J.-Y. Wang and J. Pei. Chem Asian J,
2017, 12, 302-307.
[2] Y.-Z. Dai, N. Ai, Y. Lu, Y.-Q. Zheng, J.-H. Dou, K. Shi, T. Lei, J.-Y. Wang and J. Pei. Chem. Sci. 2016,
7, 5753-5757.
114
P2: Study the thermoelectric properties under photoexcitation based on the
CH3NH3PbI3 polycrystalline thin films
Ling Xu*,
Ping Wu, Yan Xiong
Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology,
Wuhan 430074, China
E-mail: [email protected] (L.Xu)
This article reports using photoexcitation-generated excited states to adjust CH3NH3PbI3 polycrystalline
thin film’s thermoelectric properties, we found that photoexcitation can simultaneously increase its
Seebeck coefficient and electrical conductivity with multilayer electrode/polymer/electrode thin-film
design. Our experimental results show that photoexcitation can increase the Seebeck coefficient from 26
µV/K to 17 mV/K with increasing light intensity from 0% to 100%.
Simultaneously, the electrical conductivity is also increased from7.8×10-6
S/m in the dark to 4×10-5
S/m
in illumination condition. The Power Factor (PF) value of 11.51 nW/mK2
in the excited state is further
bigger than the PF of 5.27×10-6
nW/mK2
in the dark condition. We know traditional doping leads to
increased electrical conductivity but decreased Seebeck coefficient, which limits the enhancement of
power factor. In the CH3NH3PbI3，the excitons generated by the photoexcitation in the perovskite film can be
easily converted into free electrons and holes to increase the carrier concentration, then enhancing the
electrical conductivity. In addition, we found that the photoexcitation can effectively restrain the Seebeck
coefficient reduction for the phase structure change. As a result, our experiment further demonstrate that an
photoexcitation can used as an effective way to simultaneously develop high Seebeck coefficient and electrical
conductivity through excited states in an organic semiconducting materials with multilayer
electrode/polymer/electrode thin-film devices. Simultaneously, it is also develop and enhance organic-
inorganic hybrid perovskite thermoelectric properties as some contribution.
Keywords: CH3NH3PbI3 polycrystalline thin-films; photoexcitation generate excited state; Seebeck
coefficient; electrical conductivity
115
P3: An experimental study on thermoelectric properties of graphene modulated
by ferroelectric gate FET
Yutaro Fujisaki1, Hikaru Horii
2, Masahiro Ito
2, Satoru Konabe
2, Takahiro Yamamoto
2, Yoichiro Hashizume
1,
Takashi Nakajima1,3
, and Soichiro Okamura1
1 Faculty of Science, Tokyo University of Science, Japan 2 Faculty of Engineering, Tokyo University of Science, Japan
3JST PRESTO E-mail: [email protected]
Graphene, a two-dimensional material, is known to have excellent thermoelectric characteristics by
modulating its carrier density and to exhibit ambipolar characteristics in a Field Effect Transistor (FET). [1]
However, power consumption induced by gate voltage of FET is inefficient for the thermoelectric energy
conversion. To solve this problem, we used a ferroelectric as the gate because the ferroelectric gate makes it
possible to modulate the carrier density of graphene without electric power. As a pioneering research, the
carrier density of single-walled carbon nanotubes has been changed by using the same method. [2]
To realize
this concept, we fabricated a sample with a Metal-Ferroelectric-Semiconductor transistor (MFS-FET)
structure (Fig. 1) using the following steps. First, the vacuum deposition of gold source and drain electrodes
with a 1.5 mm gap was performed onto a single layer graphene (SLG) on a SiO2 / Si substrate. Next, a thin
film of vinylidene fluoride (VDF) / trifluoroethylene (TrFE) (75/25 mol%) copolymer was formed as the
ferroelectric layer by spin coating, and a crystallization annealing was carried out at 140 °C. Finally, Al was
deposited under vacuum as the gate electrode.
Figure 1. Schematic image of the MFS-FET structure to
modulate the carrier density of the Graphene layer. Figure 2. IDS-VG curve of Graphene layer and D-VG
hysteresis curve of ferroelectric VDF-TrFE on MFS-FET.
The results of the IDS-VG characteristics of the graphene layer and the D-VG hysteresis loop of the VDF / TrFE
on MFS-FET are shown in Fig. 2. It is confirmed that the characteristics of the polarization reversal were
consistent with the results obtained in metal electrode samples. Also, IDS drastically changed near the coercive
voltage, and carrier injection to SLG due to ferroelectric polarization was clearly observed. Table 1 shows the
Seebeck coefficient of SLG measured at average temperature of 40°C when the directions of the polarization
were changed. Compared to non-poling, the Seebeck coeficient decreased by 5.58% when the polarization
direction was upward, but increased by 17.9% when the polarization switched to downward. Therefore, it was
concluded that the ferroelèctric gate FET is available for modulating the thermoelectric
properties of SLG
[1] Y. M. Zuev et al., Phys. Rev. Lett, 2009, 102, 096807.
[2] S. Horike et al., Appl. Phys. Express, 2016, 9, 081301.
116
P4: On the Manifestation of Electron-Electron Interactions in the Thermoelectric
Response of Semicrystalline Conjugated Polymers with Low Energetic Disorder
M. Statz1, D. Venkateshvaran
1, H. Sirringhaus
1 and R. Di Pietro
2
1University of Cambridge, Cavendish Laboratory, J. J. Thomson Avenue, CB3 0HE Cambridge, UK
2Hitachi Cambridge Laboratory, J. J. Thomson Avenue, CB3 0HE Cambridge, UK
E-mail: [email protected]
The recent development of amorphous and semicrystalline polymer semiconductors with low energetic
disorder and saturation mobilities exceeding those of amorphous silicon has highlighted the limitations of a
description of charge transport based on disorder, and requires us to rethink how charge carriers are transported
in these materials.[1, 2]
We study the charge carrier density and temperature dependence of electron mobility and Seebeck coefficient
in the semicrystalline polymer P(NDI2OD-T2) with varying degrees of crystallinity using a thin-film-transistor
structure. This architecture allows us to measure the two transport coefficients on the very same device,
enabling us to characterize the type of transport and density of states of the material. While the different degree
of crystallinity significantly impacts the charge carrier density dependence of the mobility, the Seebeck
coefficient is temperature independent, follows Heikes' formula and has the same magnitude for different
degrees of crystallinity. This result is not compatible with charge transport being limited by energetic disorder
effects and is a direct evidence for narrow band conduction in semicrystalline polymer semiconductors.
Furthermore, it envisions how tuning the crystallinity can be employed to selectively tune the transport
coefficients and thereby significantly enhance the power factor for efficient thermoelectric generators.
We show that a consistent description of the measured transport coefficients in semicrystalline polymer
semiconductors requires the consideration of a spatially inhomogeneous and explicitly charge density
dependent density of states (Fig.1). We present a formalism considering electron-electron interactions as a
route to incorporate the physics of an explicitly charge density dependent density of states. This new
interpretation of charge transport has profound consequences on all aspects of polymer semiconductor
electronics and can lay the foundation of a further dramatic improvement in performance of this class of
materials.
Fig. 1: Seebeck coefficient versus conductivity as well as the fits with various transport models including the approach that considers electron-electron interactions (CET)
[1] D. Venkateshvaran, M. Nikolka, A. Sadhanala, V. Lemaur, M. Zelazny, M. Kepa, M. Hurhangee, A. J. Kronemeijer, V. Pecunia, I. Nasrallah, I. Romanov, K. Broch, I. McCulloch, D. Emin, Y. Olivier, J.
Cornil, D. Beljonne and H. Sirringhaus, Nature, 2014, 515, 384.
[2] R. Di Pietro, I. Nasrallah, J. Carpenter, E. Gann, L. S. Kölln, L. Thomsen, D. Venkateshvaran, K. O'Hara,
A. Sadhanala, M. Chabinyc, C. R. McNeill, A. Facchetti, H. Ade, H. Sirringhaus and D. Neher, Adv.
Funct. Mater., 2016, 26, 8011.
117
P5: Analytical approach to thermoelectric properties of carbon nanotube thin
film using a random graph theory
Yoichiro Hashizume1, Masaaki Tsukuda
2, Takahiro Yamamoto
2, Takashi Nakajima
1,3, and Soichiro Okamura
1
1 Faculty of Science, Tokyo University of Science, Katsushika, Tokyo 125-8585, Japan
2Faculty of Engineering, Tokyo University of Science, Katsushika, Tokyo 125-8585, Japan
3PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
E-mail: [email protected]
Recently, carbon nanotube (CNT) has been attracting much attention as a building nanoblock of high
performance thermoelectric materials. In fact, CNT thin films, which are aggregations consisting of a large
amount of CNTs, are promising candidates for flexible and high-performance thermoelectric materials.
However, due to complexity of CNT thin films, the physical origin of their high thermoelectric performance
remains to be elucidated yet. Thus, we provide an analytical approach to understand the thermoelectric
properties of CNT thin film based on a random graph theory.
In the present study, we assume CNTs are randomly distributed on the CNT thin film and they construct a
network. To treat the CNT network by statistical theory, the CNT network is transformed into a node-edge
graph as shown in Fig. 1. On this transformation, the CNT in a network is expressed by a node, while the
connection between two CNTs is expressed by an edge between two nodes. This transformation holds the one
to one correspondence, that is, a two-dimensional CNT network is described by the random network with nnodes i , where n denotes the number of CNTs per unit area. We assume the existence probability p
(which is constant) of the edge between two nodes i and j . This kind of the network is called as “Erdős–
Rényi model”[1]
. The degree ik is defined as the number of edges connected to the node i . From the study by
Erdős and Rényi[1]
, the average degree ik is given by the number density n of the nodes as npki . And
the critical probability Cp of the percolation transition is also given as
Then, at the percolation threshold, the average degree is obtained as
Thus, at the critical point, one CNT crosses with log n other CNTs. For example, when 220 CNTs with 1 μm
length are randomly distributed in 4 μm2 area, Eq.(2) suggests that a CNT on the system meets about 4 other
CNTs. This estimation is critically supported by numerical simulation. In our presentation, we will discuss the
physical properties based on the above network model.
Figure 1. Transformation of CNT distribution into node-edge graph
[1] P. Erdős and A. Rényi, Publicationes Mathematicae, 1959, 6, 290–297
.log
Cn
np
.logC nnpki
)1(
)2(
118
P6: Facile Fabrication of PEDOT:PSS/SWCNT Composite Film with High
Thermoelectric Properties
Ichiro Imae, Lu Zhang, and Yutaka Harima
Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, 1-4-1
Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan
E-mail: [email protected]
Since the pioneering works of thermoelectric materials based on the conducting polymers were reported
at the end of 20 centuries, several types of conducting polymers have been applied to the thermoelectric
materials due to their advantages of light weight, flexibility, low cost, and low toxicity compared over the
inorganic materials. Very recently, it was found that a commercially available conducting polymer,
poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), showed an excellent performance,
which activated the research field of the organic-based thermoelectrics. However, the performances are still
insufficient from the viewpoint of their practical uses. One possible way to enhance the thermoelectric
properties of conducting polymers is to combine them with highly conductive carbon nanotubes, but the
methods to prepare the composites of conducting polymers and carbon nanotubes are mostly complicated. In
this presentation, we demonstrate a more facile method to fabricate the composite films of PEDOT:PSS and
single-wall carbon nanotube (SWCNT) [1,2]
.
The composite films were prepared by a doctor-blade method from the mixture solution of PEDOT:PSS
and SWCNT water dispersion solutions. The electrical conductivities of the composites increased with
increasing the mass fraction of SWCNT (WSWCNT), and showed a maximum at WSWCNT =74 wt%. To eliminate
the insulating surfactant, which was introduced in SWCNT solution, the composite films were dipped in
DMSO solvent. The film morphologies were drastically changed after the removal of the surfactant (Figure 1).
The electrical conductivities were enhanced by the removal of the insulating surfactant, and showed 3800 S/cm
at WSWCNT = 74 wt% (Figure 2).
(a) (b)
Figure 1. FE-SEM images of PEDOT:PSS/SWCNT composite film (a) before and (b) after washing with DMSO.
(a) (b)
Figure 2. Changes of (a) σ and S, and (b) PF of PEDOT:PSS/SWCNT composite films washed with DMSO.
[1] Y. Harima, I. Imae, Y. Sakurai, J. Watanabe, K. Goto, Pat. P., 2017-155925 (2017).
[2] L. Zhang, Y. Harima and I. Imae, Org. Electron., 51, 304 (2017).
119
P7: Thermoelectric Properties of Solution-Processed n-Doped Ladder-Type
Conducting Polymers
Suhao Wang1, Magnus Berggren
1, Xavier Crispin
1, Daniele Fazzi
2, and Simone Fabiano
1
1 Department of Science and Technology, Linköping University, Norrköping SE-60174, Sweden 2Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany
E-mail: [email protected]
Recently, conducting polymers have been identified as potential thermoelectric materials for the low
temperature range.[1] Building efficient thermoelectric devices requires high-performance complementary p-
type and n-type materials. However, this is limited by the n-type organic semiconductors, which typically
suffer from a low electron conductivity, primarily due to their low electron affinity that strongly restricts
the n-doping level. Moreover, the relationship between chemical structure, polaron
localization/delocalization, and doping efficiency remains unclear.
Figure 1. Torsion-free ladder-type BBL can outperform distorted donor–acceptor P(NDI2OD-T2) in conductivity
and thermoelectric power factor
Here, we demonstrate that linear – “torsion-free” – ladder-type conducting polymers, such as BBL, can
reach conductivity values that are three orders of magnitude higher than those of distorted donor– acceptor
polymer [e.g., P(NDI2OD-T2)].(Figure 1) The computed polaron and spin delocalization lengths are larger
in BBL than in P(NDI2OD-T2), suggesting an easier intramolecular transfer, thus a higher polaron mobility
along the chain in BBL. Hereby, the high electron conductivity of BBL can be already rationalized at the
single-chain level. The optimized power factor of BBL reaches values that are one order of magnitude
higher. These results provide a simple picture that clarifies the relationship between the backbone
structure of the polymer and the polaron delocalization length, setting molecular-design guidelines for the
next generation of conjugated polymers.
[1] O. Bubnova, Z. U. Khan, A. Malti, S. Braun, M. Fahlman, M. Berggren, X. Crispin, Nat. Mater. 2011,
10, 429.
[2] S. Wang, H. Sun, U. Ail, M. Vagin, O. Å. Persson, J. W. Andreasen, W. Thiel, M. Berggren, X. Crispin, D.
Fazzi, S. Fabiano, Adv. Mater., 2016, 28, 10764.
120
P8: High Power Factor, Completely Organic Thermoelectric Nanocoatings for
Flexible Films and Textiles
Chungyeon Choa, Choongho Yu
a, JaimeC.Grunlan
a,b,c
aDepartment of Mechanical Engineering, Texas A&M University, College Station, TX, USA
bDepartment of Materials Sci. and Eng., Texas A&M University, College Station, TX, USA
cDepartment of Chemistry, Texas A&M University, College Station, TX, USA
E-mail: [email protected]
In an effort to create a paintable/printable thermoelectric material, comprised exclusively of organic
components, polyaniline (PANi), graphene, and double-walled carbon nanotubes (DWNT) were
alternately deposited from aqueous solutions using the layer-by-layer assembly technique.[1] Graphene and
DWNT are stabilized with an intrinsically conductive polymer, poly(3,4-
ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). A 1 µm thick film, composed of 80
PANi/graphene-PEDOT:PSS/PANi/DWNT-PEDOT:PSS quadlayers (QL) exhibits electrical
conductivity (σ) of 1.88 x 105 S/m and a Seebeck coefficient (S) of 120 µV/K, producing a thermoelectric
power factor (S2∙σ) of 2710 µW/(m∙K2). This is the highest value ever reported for a completely organic
material measured at room temperature. Furthermore, this performance matches or exceeds that of
commercial bismuth telluride. These outstanding properties are attributed to the highly ordered structure
in the multilayer assembly. The thermoelectric power output increased with the number of cycles
deposited, yielding 8.5 nW at 80 QL for ΔT = 5.6 K. A simple thermoelectric generator was prepared with
selectively-patterned, fabric-based system. The electric voltage generated by each TE device increased in
a linear relationship with both ΔT and the number of TE legs, producing ~ 5 mV with just five legs and a ΔT
of 9.7 K, as shown in Figure 1. By stabilizing, nanotubes and graphene with nitrogen-rich molecules, n-
type multilayer thin films with relatively high power factor have also been produced.[2] This unique TE
coating system is water-based and uses only organic components. For the first time, there is a real
opportunity to harness waste heat from unconventional sources, such as body heat to power devices in an
environmentally-benign way.
Figure 1. Thermoelectric voltage generated by a cotton fabric-based device measured at an ambient temperature
of 25.6 °C. With a ΔT of 9.7 K, this device generates 5.10 mV, corresponding to a Seebeck coefficient of 105
µV/K
[1] C. Cho, K. L. Wallace, P. Tzeng, J.-H. Hsu, C. Yu, J. C. Grunlan, Adv. Energy Mater., 2016, 6,
1502168.
[2] C. Cho, M. Culebras, K. L. Wallace, Y. Song, K. Holder, J.-H. Hsu, C. Yu, J. C. Grunlan, Nano Energy,
2016, 28, 426 - 432.
121
P9: Synthesis, Characterization, and Thermoelectric Performance of π-
Conjugated Polymers with Metal-Bis(dithiolene) Units
Nana Toyama1, Kazuki Ueda
1, Mika Oku
1, Masahiro Muraoka
1, and Michihisa Murata
1,2
1 Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology, 5- 16-1
Omiya, Asahi-ku, Osaka 535-8585, Japan 2 PRESTO, Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332- 0012,
Japan
E-mail: [email protected]
One-dimensional (1D) polymers[1-3] that consist of π-conjugated metal–bis(dithiolene) units have received
significant attention on account of their unique properties, which include high conductivity, and due to their
potential use in organic thermoelectric materials.
Although a 1D metal–bis(dithiolene) polymer with tetrathiooxalate (tto) ligands has shown high
thermoelectric performance,[4] examples of such 1D conductive polymers remain limited, most likely due to
a lack of versatile methods for the preparation of oxygen-sensitive tetrathio ligands.[5] In a different
context, we have developed an improved method for the synthesis of structurally well- defined
multimetallic gold–bis(dithiolene) complexes, which led to the formation of 1D rod-shaped and 2D starburst
structures as potential precursors for molecular conductors.[6]
In this study, we initially prepared π-conjugated bridging units, which contained cyanoethyl- protected
thiol groups, by Pd-catalyzed cross coupling reactions as air-stable precursors. These precursors were
subsequently converted into metal-coordinating polymers in one pot (Figure 1). For example, yellow
solutions of coordination oligomers or polymers with benzene-tetrathiolate ligands[2,3] were obtained from
treating these precursors with CuCl2·2H2O in the presence of the phosphazene base at room temperature.
A subsequent oxidation in air furnished dark brown polymeric solids. The characterization and the
thermoelectric performance of these polymers will be discussed in this presentation.
Figure 1. Synthesis of metal–bis(dithiolene) oligomers/polymers using the bridging units with cyanoethyl-
protected thiol groups.
[1] H. Poleschner, W. John, F. Hoppe, E. Fanghänel, S. Roth, J. Prakt. Chem. 1983, 325, 957-975.
[2] C. W. Dirk, M. Bousseau, P. H. Barrett, F. Moraes, F. Wudl, A. J. Heeger, Macromolecules 1986, 19,
266-269.
[3] R. Matsuoka, R. Sakamoto, T. Kambe, K. Takada, T. Kusamoto, H. Nishihara, Chem. Commun. 2014, 50,
8137-8139.
[4] Y. Sun, L. Qiu, L. Tang, H. Geng, H. Wang, F. Zhang, D. Huang, W. Xu, P. Yue, Y.-s. Guan, F. Jiao, Y.
Sun, D. Tang, C.-a. Di, Y. Yi, D. Zhu, Adv. Mater. 2016, 28, 3351-3358.
[5] C. W. Dirk, S. D. Cox, D. E. Wellman, F. Wudl, J. Org. Chem. 1985, 50, 2395-2397.
[6] M. Murata, S. Kaji, H. Nishimura, A. Wakamiya, Y. Murata, Eur. J. Inorg. Chem. 2016, 3228-3232.
122
P10: Thermoelectric properties of a semi conducting compound CoSb3 doped
with Sn and Se
Mohamed Chitroub
Ecole National Polytechnique, Algeria. E-mail: [email protected]
Hot-pressed samples of the semi-conducting compound CoSb3 with the stoichiometric composition doped
with Sn and Se were prepared and characterized by X-ray and microprobe analysis. Thermoelectric
characterization was done through measurements of the electrical and thermal conductivities as well as the
Seebeck coefficient between room temperature and 900K. All samples had n-type conductivity. The
dimensionless thermoelectric figure of merit ZT increases with increasing temperature and reaches a
maximum value of 1.3 at 873K.
Keywords: Semiconductors; Thermoelectric; Hot pressing; CoSb3; Skutterudite.
123
P11: Effects of CNT Type, Processing, and Doping on Thermoelectric
Performance
Bernhard Dörling1, Osnat ZapataArteaga
1 and Mariano CampoyQuiles1
1Materials Science Institute of Barcelona (ICMABCSIC), Campus of the UAB, 08193 Bellaterra, Spain
Email: [email protected]
Carbon nanotubes (CNTs) are a promising organic thermoelectric material. They have a high electrical
conductivity σ as well as a potentially high Seebeck coefficient S due to their nature as one dimensional conductors. S is
known to depend on the specific type of CNT, with the mainly metallic multiwalled CNTs performing worse than the
more semiconducting singlewalled CNTs,[1] as shown in Figure 1. Ideally, only semiconducting SWCNTs with identical
chiral vector should be used. But in practice, there are several more obstacles that have to be overcome before CNT
thermoelectrics can reach their full potential. For best performance, CNTs should be long and highly disperse to maximize
σ; as well as accurately doped, to reach the highest possible S.
Here we report results of the electrical conductivity and the Seebeck coefficient for different types of commercially
available CNT raw materials. We compare the influence of different dispersion methods, and report on combined
dispersingdoping approaches. In that case, the materials that are used to disperse the nanotubes in solution during
processing partially remain in the dried film, where they serve as dopant.
Figure 1. Thermoelectric performance grouped by type of carbon nanotubes.
[1] B. Dörling, S. Sandoval, P. Kankla, A. Fuertes, G. Tobias, M. Campoy-Quiles, Synth. Met. 2017, 225, 70–75.
124
P12: Evaluation of conductivity L11 and thermoelectric coefficient L12 by current-
voltage measurement
Takashi Nakajima
1,4, Takahiro Yamamoto
2, Yoichiro Hashizume
1, Masahiro Ito
1,2, Takashi Utsu
1, Keishi
Nishio3, Hidetoshi Fukuyama
1, and Soichiro Okamura
1
1 Faculty of Science, Tokyo University of Science, Japan
2 Faculty of Engineering, Tokyo University of Science, Japan
3 Faculty of Industrial Science and Technology, Tokyo University of Science, Japan
4 PRESTO, Japan Science and Technology Agency, Japan
E-mail: [email protected]
Thermoelectric materials have been the subjects of extensive investigations owing to their functional
properties and the prospects for the emerging energy harvesting devices. A key parameter of a thermoelectric material is the Seebeck coefficient, 𝑆 = −(∆𝑉 ∆𝑇⁄ )𝐽=0, which can be determined to measure the voltage V induced by a temperature difference T under open-circuit condition (i.e., J = 0). In contrast, the current density J induced by the thermoelectric effect can be described as
[1,2]
𝐽 = 𝐿11𝐸 −𝐿12
𝑇
𝑑𝑇
𝑑𝑧 (1)
for the linear response with respect to the electric field E and the temperature gradient dT/dz. Here, L11 is the
electric conductivity and L12 is the thermoelectric coefficient. Thus, S is rewritten as
𝑆 =1
𝑇
𝐿12
𝐿11 (2)
by eq. (1). Therefore, evaluating the L11 and L12 is essentially important to understand the origin of the Seebeck
coefficient. Thus, in this study, we have focused on developing the experimental method to evaluate L11 and
L12 by a current (I) - voltage (V) measurement. The measurements were performed in the lab-made system. A Mg2Si bulk sample fabricated by a spark
plasma sintering method was clamped between holders and a temperature difference was given by a heater and a water cooler. The current-voltage characteristics were evaluated by a source measure unit (Keysight B2911) with 4 or 2 wire setup. Figure 1 shows the results for the I-V measurements with T ranging from 1 to 9 K. It was clearly observed that the I-V curve shifted as T increased. As shown eq. (1), the inclination of the I-V curve gives L11, and the intersection of the current axis, L12. Therefore, the curve shift is interpreted as the change of the current induced by the thermal driving force. After fitting the I-V curves by linear regression, the linear function L11 and L12 were obtained as shown in Fig.2. The increase of L11 and the decrease of L12 with increasing the average temperature was observed in the narrow temperature range. The Seebeck coefficient calculated by eq. (2) was -333 V/K at the average temperature of 296 K. It was 9.0% lower than that obtained by the conventional thermo-electric measurement system ZEM-2. The experimental accuracy in this measurement will be discussed on the basis of the setup for the electric measurement, the temperature mea-surement, and the effect of the contact resistance for the L12 evaluation.
[1] M. Jonson and G. D. Mahan, Phys. Rev. B 1980 21, 4223.
[2] T. Yamamoto and H. Fukuyama, J. Phys. Soc. Jpn, submitted
-200
-150
-100
-50
0
I (
-1.0 -0.5 0.0 0.5 1.0
V (mV)
T = 1 K
T = 9 K
Fig.1 Temperature
difference dependence of I-
V curves for Mg2Si.
170
168
166
164
162
160
L1
1 (
S/m
)
296295294293
Average Temparature (K)
-20
-18
-16
-14
-12
-10
L1
2 (A/m
)
L11
L12
Fig.2 Average temperature
dependence of L11 and L12
of Mg2Si.
125
P13: Investigation of Contact Resistance in Organic Thermoelectric Devices
Juhyung Park, Jaeyun Kim, Jeonghun Kwak*
School of Electrical and Computer Engineering, The University of Seoul, Seoul 02504, South Korea
E-mail: [email protected]
Organic thermoelectric (TE) materials have attracted a lot of attentions due to its superb properties in flexibility, eco-friendliness, and cost-efficiency. Significant progress in their TE properties has been made
owing to the multilateral efforts to develop novel materials as well as to understand the electrophysical
characteristics in recent years.[1–3]
As results, the figure of merit of some organic materials is approaching
that of inorganic materials. However, contrary to the inorganic TE devices,[4]
there are few studies covering
the electrical contact resistance between electrodes and an active layer for organic TE devices. Because of the difference of the Fermi energy levels between a metal and a semiconductor, the carriers generated by the thermal gradient should overcome the potential barrier at the interface to flow current. The contact resistance is thus critical not only for the performance of TE devices but also for the practical realization of organic TE generators consisting of several TE devices connected in series. In this work, we investigated the electrical contact resistance of poly(3,4- ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) based TE devices with electrical and spectroscopic measurements. We also observed the effect of the work function
of electrodes on the contact resistance. By minimizing the energy barrier at the metal–semiconductor interface, the Seebeck coefficient of the PEDOT:PSS based TE device was increased by 10.3% compared to the normal device. In the presentation, we will discuss on the detailed results of the contact resistance and the performance of PEDOT:PSS based TE devices.
[1] O. Bubnova, Z. U. Khan, A. Malti, S. Braun, M. Fahlman, M. Berggren, X. Crispin, Nat. Mater., 2011,
10, 429.
[2] C. Warwick, D. Venkateshvaran, H. Sirringhaus, APL Mater., 2015, 3, 096104.
[3] S. D. Kang, G. J. Snyder, Nat. Mater., 2017, 16, 252.
[4] L. W. da Silva, M. Kaviany, Int. J. Heat Mass Transfer, 2004, 47, 2417.
126
P14: Half-metallic completely compensated ferrimagnets in Cr doped BaP
A. Bouabca1 H.Rozale
1 WangX.T2 A.Sayade
3
1 Condensed Matter and sustainable development Laboratory (LMCDD), Universityof Sidi Bel-
Abbes, Sidi Bel-Abbes 22000, Algeria. 2 School of Physics and Electronic Engineering, Chongqing Normal University, Chongqing
400044, PR China. 3UCCS - ARTOIS - UMR CNRS 8181. Faculté des Sciences de Lens. Rue Jean Souvraz, France.
E-mail: [email protected]
On the basis of ab-initio calculations we have investigated the electronic and magnetic properties of Cr1-
xBaxP alloy, our calculations suggest that as we dope BaP with Cr atoms and move towards Cr1- xBaxP
where x=0, 0.125, 0.25, 0.50, and 0.75 all alloy are HM-FM. Interestingly Cr0.25Ba0.75P is a HM- AFM otherwise ‘fully compensated ferrimagnet’, this alloy should be of special interest for applications since it creates
no external stray field and thus exhibit minimal energy losses. In addition, the robustness of half-metallicity
with respect to the variation of lattice constants of Cr1-xBaxP is also discussed; moreover, ferrimagnetism co-exists with the half-metallicity, resulting in the desired fully compensated half-metallic ferrimagnetism, for a
wide range of lattice constants. Furthermore, we found that this new HMFCF is stable according to its small
formation energy.
Figure 1. Total density of state for Cr1-xBaxP alloy
[1] P. Hohenberg, W. Kohn, Phys. Rev. 1964 136, 864
[2] W. Kohn, L.J. Sham, 1965 140, A1133.
[3] E. Wimmer,H. Krakauer,M.Weinert, A.J. Freeman 1981 24, 864.
[4] John P. Perdew, Adrienn Ruzsinszky, Gabor I. Csonka, Oleg A. Vydrov, Gustavo E. Scuseria, Lucian A.
Constantin, Xiaolan Zhou, Kieron Burke, 2008 100 136406.
[5] Y. Saeed, A. Shaukat, S. Nazir, N. Ikram, Ali Hussain Reshak. Journal of Solid State Chemistry 2010 183,
242.
[6] F. D. Murnaghan, Proc. Natl. Acad. Sci. USA 1944 30, 5390.
[7] M. Sieberer, j.redinger, s.khmelevskyi and p.mohn 2006 73,024404.
[8] G. rahman 2010 81 ,134410.
[9] R. A. de Groot, F. M. Mueller, P. G. v. Engen, and K. H. J.Buschow 1983 50,2024.
[10] Emmanuel Favre-Nicolin, These de doctorat, Universite Grenoble I - Joseph Fourier 2003 91, 037204.
[11] J.E. Pask, L.H. Yang, C.Y. Fong, W.E. Pickett, S. Dag 2003 67, 224.
127
P15: High pressure study of vibrational properties of methylammonium lead
iodide perovskites
Adrian Francisco López1, Bethan Charles
2, Oliver Weber
2, M. Isabel Alonso
1, Miquel Garriga
1, Mariano
Campoy-Quiles1, Mark Weller
2, Alejandro R. Goñi
1,3
1Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), 08193 Bellaterra, Spain
2University of
Bath, Centre for Sustainable Chemical Technologies, Bath BA2 7AY, UK 3ICREA, Passeig Lluís
Companys 23, 08010 Barcelona, Spain
E-mail: [email protected]
Hybrid lead halide perovskites have drawn lots of attention as a very promising photovoltaic material,
exhibiting extremely high efficiencies exciding 20% after a few years of development. Recently, the interplay
between the vibrational spectrum and the dynamic disorder caused by the organic cations has been studied
in methylammonium lead iodide (MAPI) as a function of temperature by means of Raman scattering [1]
. At
room temperature, MAPI adopts a tetragonal crystal structure in which the organic cations can move freely
within the perovskite cage voids. However, at about 162 K, MAPI transforms to an orthorhombic phase in
which the inorganic cage reduces its volume and symmetry, locking the methylammonium (MA) molecules
inside the voids, reducing drastically the inhomogeneous broadening of the inorganic cage phonons [1]
. This
effect is expected to play a key role for the thermal properties of the material. Another way to influence the
crystal structure of a material and, concomitantly, the vibrational properties is by using high hydrostatic
pressure which allows for the controlled variation of the lattice constant by a few percent. Here we present
results from Raman measurements on MAPI single crystals for pressures up to 5.7 GPa. In this pressure range
we observe several phase transitions at 0.4, 2.75 and 3.4 GPa, as indicated by the sudden change in the
number and frequency of phonon modes (see Fig. 1), as observed by Raman. In particular, the transition
occurring at 2.75 GPa involves a massive reduction of the phonon linewidths, which is
phenomenologically similar to the one observed at the tetragonal-to-orthorhombic transition at low
temperatures. Interestingly, we could not find any amorphization of the sample in the whole pressure range of
the experiment, in contrast to the reports of the literature [2]
. We discuss the impact of these findings on the
lattice thermal properties of hybrid perovskites.
Fig. 1: Raman mode frequencies of the inorganic cage phonons of MAPI as a function of pressure. Pressures at
which a phase transition occurs are indicated by vertical dotted lines. The transition at 2.75 GPa involves a
reduction of the phonon linewidths, probably with impact on thermal conductivity.
[1] Leguy, A.M.A. et al., Phys. Chem. Chem. Phys. 2016, 18, 27051–27066.
[2] Postorino, P. & Malavasi, L., J. Phys. Chem. Lett. 2017, 8, 2613–2622.
128
P16: Investigation of Contact Resistance in Organic Thermoelectric Devices
Juhyung Park, Jaeyun Kim, Jeonghun Kwak*
School of Electrical and Computer Engineering, The University of Seoul, Seoul 02504, South Korea
E-mail: [email protected]
Organic thermoelectric (TE) materials have attracted a lot of attentions due to its superb properties in flexibility, eco-friendliness, and cost-efficiency. Significant progress in their TE properties has been made owing to the multilateral efforts to develop novel materials as well as to understand the electrophysical
characteristics in recent years.[1–3]
As results, the figure of merit of some organic materials is approaching
that of inorganic materials. However, contrary to the inorganic TE devices,[4]
there are few studies covering
the electrical contact resistance between electrodes and an active layer for organic TE devices. Because of the difference of the Fermi energy levels between a metal and a semiconductor, the carriers generated by the thermal gradient should overcome the potential barrier at the interface to flow current. The contact resistance is thus critical not only for the performance of TE devices but also for the practical realization of organic TE generators consisting of several TE devices connected in series. In this work, we investigated the electrical contact resistance of poly(3,4- ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) based TE devices with electrical and spectroscopic measurements. We also observed the effect of the work function of electrodes on the contact resistance. By minimizing the energy barrier at the metal–semiconductor interface, the Seebeck coefficient of the PEDOT:PSS based TE device was increased by 10.3% compared
to the normal device. In the presentation, we will discuss on the detailed results of the contact resistance and the performance of PEDOT:PSS based TE devices.
[1] O. Bubnova, Z. U. Khan, A. Malti, S. Braun, M. Fahlman, M. Berggren, X. Crispin, Nat. Mater., 2011,
10, 429.
[2] C. Warwick, D. Venkateshvaran, H. Sirringhaus, APL Mater., 2015, 3, 096104.
[3] S. D. Kang, G. J. Snyder, Nat. Mater., 2017, 16, 252.
[4] L. W. da Silva, M. Kaviany, Int. J. Heat Mass Transfer, 2004, 47, 2417.
129
P17: Improvement of Thermoelectric properties of polymeric PEDOT:Tos based
devices
Geoffrey Prunet
1, Eric Cloutet
1, Guillaume Fleury
1, Eleni Pavlopoulou
1, Stephane Grauby
2, Stefan Dilhaire
2
and Georges Hadziioannou1
1 Laboratoire de Chimie des Polymères Organiques (LCPO) UMR 5629, Université de Bordeaux, 16
Avenue Pey-Berland Pessac CEDEX, F-33607, France 2 Laboratoire Ondes et Matière d’Aquitaine (LOMA) UMR 5798, Université de Bordeaux, 351 avenue de
la Libération Talence CEDEX, F-33405, France
E-mail: [email protected]
Conducting polymers have gained the attention of the scientific community due to their prospective use in
thermoelectric applications. [1] In this work we explore various ways for enhancing the conductivity (σ) or the
Seebeck coefficient (S) of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with p-toluenesulfonate (Tos)
thin films, in order to achieve an overall increase of the power factor 𝑆²𝜎. We engineer the structure of
PEDOT:Tos thin films by the addition of high-boiling point additives [2] and/or bases and we study the
structural, electrical and thermoelectric properties of the films by mean of grazing incidence wide angle x-
ray scattering, conductivity measurements, Seebeck coefficient measurements and x-ray photoelectron
spectroscopy. Our results show an improvement of the crystallization characteristics of PEDOT:Tos, which
induces an increase in conductivity and, thus, an increase of the power factor. Furthermore, hybrid devices based
on silicon or gallium arsenide and PEDOT:Tos were fabricated and have been studied as an alternative means to
further enhance the thermoelectric efficiency of the polymeric material.
[1] O. Bubnova, Z. U. Khan, A. Malti, S. Braun, M. Fahlman, M. Berggren and X. Crispin. Nat. Mater.,
2011, 10, 429–433.
[2] I. Petsagkourakis, E. Pavlopoulou, G.Portale, B. A. Kuropatwa, S. Dilhaire, G .Fleury and Hadziioannou.
Scientific Reports, 2016, 6, 30501.
130
P18: Preparation of colloidal silica using the biomimetic synthesis
Kyoung-Ku Kang and Chang-Soo Lee*
Department of Chemical Engineering and Applied Chemistry, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea.
E-mail: [email protected]
Silica is one of the most abundant elements on the planet and is the inorganic material that mankind is
making the most use of together with iron.[1] Therefore, the various forms of silica can be used for the required
application. Among these, colloidal silica has useful advantages, such as large surface areas, low toxicity,
high biocompatibility, optically high transparency, high chemical stability, and high thermal stability.
However, most of the conventional silica has prepared under harsh conditions.[2,3] Here we suggest the
biomimetic synthesis method of colloidal silica, which can be carried under mild condition.[4] The synthesis of colloidal silica was carried out by using TEOS (tetraethyl orthosilicate) and PAH (polyallylamine
hydrochloride/substitute for proteins of biosilicification) under various synthesis conditions. According to the
results, the PAH can accelerate the condensation of hydrolyzed TEOS in acidic and neutral conditions and
promote the creation of nuclei of the silica particles. The synthesized silica particles exhibited various
shapes, such as sponge-like, self-assembled, irregular spherical and completely spherical shapes and these
various shape could be controlled by simple change of synthesis parameters. In particular, depending on the
concentration of PAH in mother liquor, it was possible to obtain nearly perfect spherical-shaped silica
nanoparticles with uniform sizes. Consequently, we can closely approach to understanding the ability of
proteins of biosilicification using PAH as a replacement of these proteins.
SEM images of colloidal silica synthesized by biomimetic synthesis
[1] P. Treguer, D.M. Nelson, A.J. Vanbennekom, D.J. Demaster, A. Leynaert, B. Queguiner, The Silica
Balance in the World Ocean - a Reestimate, Science, 1995, 268, 375-379.
[2] L.L. Hench, J.K. West, The sol-gel process, Chem. Rev., 1990, 90, 33-72. [3] C.J. Brinker, G.W. Scherer, Sol-gel science: the physics and chemistry of sol-gel processing, Academic
press 2013.
[4] C.C. Lechner, C.F. Becker, Silaffins in silica biomineralization and biomimetic silica
precipitation, Mar. Drugs, 2015, 13, 5297-5333.
131
P19: Fabrication of Flexible Organic Thermoelectric Generators by Inkjet
Printing Technique: Materials Screening and Assessment
Marco Cassinelli1, M. Massetti
1, and M. Caironi
1
1Istituto Italiano di Tecnologia (IIT), Center for Nano Science and Technology, Via Pascoli 70/3,
20133 Milan (Italy)
E-mail: [email protected]
Currently, a large percentage of energy is daily dissipated as heat to environment, e.g. within industrial
processes, without doing any useful work.[1]
Thermoelectric devices allow to recover this waste heat and
convert it into electric power through pollution-free systems with no moving fluids or mechanical parts,
making them stable and durable source of clean and sustainable energy. Nowadays, commercial micro-
thermoelectric generators based on thin film of Bi2Te3 demonstrate already the reliability of this
technology.[2]
However, the requirement of sustainability and large-scale production of the thermoelectric
technology made organic thermoelectric generators (OTEG) gaining high attention within the
thermoelectric community as based for a novel class of modules. In fact, OTEGs not only represent the
alternative to the present metal-compound thermoelectric devices, but also fulfil prerequisites that the
present technology does not satisfy, allowing the fabrication of flexible and lightweight modules
implementable where adaptability to curved and irregular surfaces and to surfaces changing in motion is
needed. Moreover, flexibility results in easier adaptability of the devices and therefore lower integration
costs.
The overarching target of this project is the fabrication of thin-film OTEGs based on conjugated
polymers by inkjet printing method. This manufacturing non-contact technique is suitable for low-cost
and large-area fabrication of flexible organic devices.[3]
Here, the first studies towards the screening and
assessment of efficient and air-stable p- and n-type thermoelectric organic materials are presented. The
materials are tested in homemade custom setups for the thermoelectric measurements.[4]
The most efficient
thermoelectric materials are then developed as ink for the printing technique, forming the legs of the
thermoelectric generators during the fabrication process.
[1] B. Gingerich et al., Environ. Sci. Tech. 2015, 49 8297.
[2] H. Bottner et al., Proc. 26th
Int. Thermoelectrics Conference 2007, pp. 306-309.
[3] M. Caironi et al., “Ink-jet Printing of Downscaled Organic Electronic Devices”, pp. 281-326 in
“Organic Electronics II” by H. Klauk, Wiley-VCH Verlag & Co., Weinheim (2012).
[4] D. Beretta et al., Rev. Sci. Instr. 2015, 86 075104.
132
P20: Different semiconducting behavior of PEDOT nanoparticles
Mario Culebras1, José F. Serrano-Claumarchirant
2, Álvaro Seijas
2, Clara M. Gómez
2, Marta Carsí
3, Maria J.
Sanchis 3 and Andrés Cantarero
4
1Stokes Laboratories, Bernal Institute, University of Limerick, Ireland
2 Institute of Material Science, University of Valencia, PO Box 22085, 46085 Valencia, Spain
3Dept of Applied Thermodynamics,Universitat Politècnica de València, Valencia, Spain
4 Molecular Science Institute, University of Valencia, PO Box 22085, 46085 Valencia, Spain
E-mail: [email protected]
Conducting polymers have attracted the attention due to their promising applications for electronic devices
such as: organic light emitting diodes (OLEDs), organic solar cell, transistors and thermoelectric devices [1]
.
Their advantages compared to inorganic semiconductors such as: flexibility, abundance, low cost and easy
chemical modification. However, n-type doping is really complicated in organic semiconductors such a
conducting polymers, since the doping mechanisms involve reduction states that are unstable at air conditions.
For this reason, there has been a big interest from the thermoelectric community in order to find a stable n-type
conducting polymer for the manufacture of thermoelectric modules using conducting polymers. As the
conducting polymers are synthetized by oxidative polymerization, it makes difficult to create negative charges
along the polymer chins for n-type behavior. In this work we report the synthesis of PEDOT nanoparticles,
being possible to control the semiconducting behavior trough the experimental conditions. The nanoparticles
were synthetized using miniemulsión methods obtaining stable suspensions that were used for producing films
by casting on a PET substrate. The electrical conductivity and the Seebeck coefficient were evaluated as a
function of the surfactant concentration used during the synthesis. The conductivity decreases three orders of
magnitude with the contraction of the surfactant while the Seebeck coefficient changes from p-type to n-type.
The doping effects were studied by Raman, UV-Vis and EPR spectroscopy.
[1] M. Culebras, C. Gómez and A. Cantarero, Materials. 2014, 7 , 6701-6732.
133
P21: Hybrid films based on PEDOT and CNTs for thermoelectric applications
José F. Serrano-Claumarchirant1, Mario Culebras
2, Rafael Muñoz-Espí
1, Marta Carsí
3, Maria J. Sanchis
3,
Clara M. Gómez1 and Andrés Cantarero
4
1 Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia, Spain
2Stokes Laboratories, Bernal Institute, University of Limerick, Ireland
3Dept of Applied Thermodynamics, Universitat Politècnica de València, Valencia, Spain
4Molecular Science Institute, University of Valencia, PO Box 22085, 46071 Valencia, Spain
E-mail: [email protected]
The depletion of classic energy sources during the last decades and the environmental problems that generate
their use, have created the necessity to look for new energy sources more sustainable and ecofriendly.
Thermoelectric generators can significantly contribute to that propose, recovering energy from waste heat. For
this reason, in the last decade thermoelectric materials have attracted a big interest in the field of energy
harvesting [1]. The thermoelectric efficiency is given by the dimensionless figure of merit ZT (ZT=S2σT/κ
where S, σ and κ are the Seebeck coefficient, the electrical and thermal conductivities, respectively).
Thermoelectric materials should not only be highly efficient, but also low-cost, manufacturing-scalable and
environmentally friendly. Conducting polymers satisfy such demands, however their thermoelectric efficiency
is very low compared to the classical inorganic thermoelectric materials. One strategy to improve the
thermoelectric efficiency of the conducting polymers is the synthesis of hybrid materials based on carbon
nanotubes. [2,3]. In this work we study the thermoelectric properties of hybrid films of PEDOT with carbon
nanotubes (MWCNT, DWCNT and SWCNT) which achieve power factor values of 72 µW·m-1
·K-2
using by
the Layer-by-Layer technique.
[1] M. Culebras, C. Gomez and A. Cantarero, Materials. 2014, 7, 6701.
[2] C. Yu, YS. Kim, D. Kim and J.C. Grunlan, Nano Lett. 2009, 9, 1283.
[3] D. Kim, Y. Kim, K. Choi, J.C. Grunlan and C. Yu, ACS Nano, 2010, 4, 513.
Figure 1. Scheme of the formation of the first bilayer of PEDOT – CNT’s.
134
P22: Towards the Fabrication of a Low Cost SnSe Thermoelectric Device
Matthew R. Burton1a
, Tianjun Liu2, Oliver Fenwick
2 and Matthew J. Carnie1
1 SPECIFIC, College of Engineering, Swansea University, Bay Campus, Fabian Way, Swansea, SA1 8EN, United Kingdom
2 School of Engineering and Materials Science (SEMS), Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
aE-mail: [email protected]
Tin selenide sparked much interest in the field of thermoelectrics when Zhao et al.[1] reported an
unprecedented ZT of 2.6 ± 0.3 at 923 K along the b axis. This discovery was observed in single crystals formed
at high temperature (1223 K) over several hours. Whilst doping tin selenide with elements such as Na[2] and
Bi[3] have also shown promising thermoelectric performance, these too were shown on single crystals with
expensive and lengthy fabrication techniques which are unfavorable for commercial applications. Chen et al.[4]
showed that a ZT of up to 0.6 can be achieved in polycrystalline tin selenide by Ag doping. The fabrication of
polycrystalline Ag doped tin selenide, however, again required lengthy and expensive fabrication techniques
unfavorable for commercial applications.
In this work, we studied the thermoelectric performance of polycrystalline tin selenide fabricated by the low-
cost thermal evaporation technique with the aim of producing a commercially viable thermoelectric device.
Thermoelectric characterization of the polycrystalline tin selenide (Fig. 1), reveals comparable power
factors to those seen on the a axis single crystal tin selenide.[1] Furthermore, initial thermal conductivity
measurements reveal substantially lower thermal conductivities than were observed for single crystal tin
selenide.[1]
Figure 1. a) Electrical conductivity, Seebeck coefficient and power factor of polycrystaline tin selenide fabricated by a
low cost commerically viable technique. These thermoelectric measuremnets were conducted on a UlvacRiko ZEM-3
instrument under a helium atmostphere. b) Initial thermal conductivity values measured on a Linseis thin film analyzer
under vacuum
[1] L.-D. Zhao, S.-H. Lo, Y. Zhang, H. Sun, G. Tan, C. Uher, C. Wolverton, V. P. Dravid, M.G. Kanatzidis,
Nature, 2014, 508, 372-377
[2] L.-D. Zhao, G. Tan, S. Hao, J. He, Y. Pei, H. Chi, H. Wang, S. Gong, H. Xu, V. P. Dravid, C. Uher, G. J.
Snyder, C. Wolverton, M. G. Kanatzidis, Science, 2015, 351, 141-144.
[3] A. T. Duong, V. Q. Nguyen, G. Duvjir, V. T. Duong, S. Kwon, J. Y. Song, J. K. Lee, J. E. Lee, S. Park, T.
Min, J. Lee, J. Kim, S. Cho, Nat. Commun., 2016, 7, 1-6.
[4] C.-L. Chen, H. Wang, Y.-Y. Chen, T. Day, and G. J. Snyder, J. Mater. Chem. A, 2014, 2, 11171-11176.
135
P23: Fabric-Type Thermoelectric Generators using Carbon-Nanotube Yarns with
Striped Doping
Takuya Koizumi1, Yuki Sekimoto
1, Mitsuhiro Ito
1, Ryo Abe
1, Hirotaka Kojima
1, Takeshi Saito
2, and
Masakazu Nakamura1
1 Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5
Takayama, Ikoma, Nara, 630-0192, Japan 2 Department of Materials and Chemistry, National Institute of Advanced Industrial Science and
Technology (AIST), Tsukuba Central 5, Tsukuba, Ibaraki, 305-8565, Japan
E-mail: [email protected]
Wide-area, low-cost, and mechanically flexible thermoelectric generators are strongly desired for the energy
harvesting from the waste heat around our lives. The performance of a thermoelectric material is generally
evaluated by the dimensionless figure of merit, ZT, and that of organic and carbon nanotube (CNT) composites
is growing rapidity [1], [2]. Although the maximum efficiency of the device with the same ZT material is often
explained to be independent of device geometry, actual efficiency in the scene of energy harvesting depends on
the entire thermal design of the device because temperature gradient in the active area is determined by the device
thickness and the thermal conductivities of components. A relatively thick active area, over 2 mm, is required
to achieve sufficient temperature gradient by considering a bottlenecking heat resistance between the device
and ambient air. However, it is not easy to fabricate such thick, flexible and uniform film by conventional
deposition processes used for thin-film devices.
In this work, we demonstrate a novel material/device design using CNT yarns with striped chemical doping for
sufficiently thick and flexible thermoelectric devices. CNT has many advantages, high electrical conductivity,
mechanical strength, high aspect ratio, and easy to fabricate CNT yarns. CNT yarns were fabricated with wet-
spinning method [3] where dispersion of CNTs in water was injected into rotating blank solution. After 24
hours, the CNT yarns were slowly extracted from the blank solution to air. The dried CNT yarns were then
wrapped around a small piece of plastic plate and dopant solution was dropped onto the one side for n-type
doping while the another side was immersed in methanol to prevent the over penetration of the dopant solution to
the original p-type area. Finally, the CNT yarns with striped doping were sewed into a felted cloth by
synchronizing the sewing pitch with the p/n-striped structure (Fig. 1). The electrical conduction through the
sewed CNT yarn was stable against repetitive bending of the cloth. Since thus fabricated “thermoelectric cloth”
is thick and thermally insulating, sufficient temperature difference between the front and back sides is formed
just by gently touching the one side of cloth in air and it generates electricity (Fig. 2).
By the various advantages of the material/device design proposed in this work, such as flexibility, stretchability,
small thermal conductivity, wiring-free for -structure formation, and the scalability both in area and thickness,
this could be a promising technology for wearable thermoelectric energy harvesting devices.
Figure 1. Fabrication methods. p-type
Figure 2. Demonstration of power generation by
the thermoelectric fabric obtained in this work.
[1] K. Suemori, S. Hoshino, and T. Kamata, "Flexible and lightweight thermoelectric generators composed
of carbon nanotube–polystyrene composites printed on film substrate," Appl. Phys. Lett., vol.103,
p.153902. 2013.
[2] Y. Nonoguchi, K. Ohashi, R. Kanazawa, K. Ashiba, K. Hata, T. Nakagawa, C. Adachi, T. Tanase, and T.
Kawai, "Systematic Conversion of Single Walled Carbon Nanotubes into n-type Thermoelectric Materials
by Molecular Dopants", Sci. Rep., vol.3, p.3344. 2013.
[3] B. Vigolo, A. Pénicaud, C. Coulon, C. Sauder, R. Pailler, C. Journet, P. Bernier, and P. Poulin.,
"Macroscopic fibers and ribbons of oriented carbon nanotubes", Science, vol.290, p.1311, 2000.
136
P24: Seebeck measurements in PEDOT:PSS thin films
Ruiz-Cózar1, G. Dalkiranis
2, A. F. Lopeandia
2, Ll. Abad
1
1 Institut de Microelectrònica de Barcelona. Centre Nacional de Microelectrònica (IMB- CNM-CSIC).
Campus de la UAB, 08193 Bellaterra, Barcelona. 2 Grupo de Nanomateriales y Microsistemas (GnaM), Dep. Física, Universitat Autònoma de
Barcelona (UAB), 08193 Bellaterra, Barcelona.
E-mail: [email protected]
In the search for new materials for clean energy conversion and gas sensing the PEDOT:PSS polymer
conductor are called to play an important role in photovoltaic as well as in thermoelectric processes. The
advantages of using organic polymers instead inorganic materials are low thermal conductivity,
abundance, non-toxicity, flexibility, low-cost, scalability, and tunable with small compositional variations.
Today the most promising TE organic materials are polyyne, polyaniline (PANI), polypyrrole (PPy),
PEDOT:PSS among others. In this work we will study PEDOT:PSS materials.
Fabrication of conducting polymeric films based on poly(3,4-ethylenedioxythiophene) (PEDOT) doped
with poly(phenylene sulfide) or PEDOT:PSS and poly (vinyl alcohol) (PVA) as a matrix has been carried
out using electrospinning and spin coating techniques. The morphology of PEDOT:PSS:PVA were studied
with scanning electron microscopy and atomic force microscopy. Electrochemical characterization has been
carried out and large differences have been obtained due to different morphology (coatings and nanofibers).
We have recently developed a setup to measure Seebeck coefficient of this thin PEDOT:PSS films and
nanofibers.
137
P25: Effect of doping-induced charge localization on thermoelectric properties of
poly(nickel-ethylenetetrathiolate)
Yunpeng Liu1, Dong Wang
1 and Zhigang Shuai1,2,
1Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China 2Key Laboratory of Organic solids, Beijing National Laboratory for Molecular Sciences (BNLMS),
Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China. E-mail: [email protected]
Doping often has a significant impact on the geometry, electronic structure, and transport properties of
thermoelectric materials. Herein, we investigate the K-doping effect on poly(nickel- ethylenetetrathiolate)
(poly[K(Ni-ett)n]), which has so far been reported with the highest figure of merit (zT) among n-type organic
thermoelectric materials.[1] According to our results, the conduction band (CB) becomes abnormally narrow
after K-doping (band width less than 1 meV when n = 20), implying the existence of charge localization.
However, such localization diminishes when n < 5. We uncover that the main cause of this localization is the
electrostatic interaction between the potassium cation and the negative charge on the polymer backbone. By
calculating the inverse participation ratio (IPR)[2]
of CB, a localization length of ~ 4.5 monomers is observed.
Taking the acoustic phonon scattering and charged impurity scattering into account, we obtained the
thermoelectric properties of poly[K(Ni-ett)n] with n ranging from 2 to 20. Among these, both electrical
conductivity and Seebeck coefficient of poly[K(Ni-ett)20] exhibit the same temperature dependence as the
experiment[1]
. Further analysis reveals that thermal activation of electrons from the localized CB to delocalized
CB+1 is responsible for such nonmonotonic temperature dependence.
Figure 1 Electrical conductivity and Seebeck coefficient of poly[K(Ni-ett)20], as functions of temperature.
[1] Y. H. Sun, L. Qiu, L. P. Tang, H. Geng, H. F. Wang, F. J. Zhang, D. Z. Huang, W. Xu, P. Yue, Y. S.
Guan, F. Jiao, Y. M. Sun, D. W. Tang, C. A. Di, Y. P. Yi, D. B. Zhu, Adv. Mater., 2016, 28, 3351-3358.
[2] M. Linares, M. Hultell, S. Stafström, Synth. Met., 2009, 159, 2219-2221
138
P26: Great enhancement of Photocatalytic and Photoelectrochemical Water
Splitting Applications of Bismuth Vanadate with Maximized Interfacial Coupling
with RGO
Tayyebeh Soltani, Byeong-Kyu Lee*
Dept. of Civil and Environment Engineering, University of Ulsan, Daehakro 93, Namgu, Ulsan 44610,
Republic of Korea
E-mail: [email protected]
With the increasing exploration and development of renewable and clean power sources, photocatalysis has
been extensively studied to solve the energy crisis and environmental pollution problems by using visible light
or solar energy. Various photocatalysts, such as TiO2, WO3, ZnO, CdS, and Ag3PO4, have been greatly
investigated as low cost and environmental-friendliness photoanode materials for photo electrochemical
(PEC) water splitting and the photocatalytic degradation of pollutants. BiVO4 (BVO), which is an intrinsic n-
type semiconductor with a direct band gap of 2.4 eV and an appropriate valance band position, has been
reported as effective visible-light-driven photocatalysts for photo degradation of pollutants and solar energy
conversion. It is because BVO has fascinating structure, excellent physicochemical properties and chemical
stability against photocorrosion. However, previous studies have proven that the performance of unmodified
nanoporous BVO photoanode is still limited due to its intrinsic slow electron transfer, which requires some
modifications of BVO structure.
In this study, a full coverage of BVO, with smaller particle size and highly strong interfacial interaction on
graphene sheet, have been successfully prepared by using visible assisted photocatalytic reduction of GO and
applied for improving the photocatalytic degradation of methylene blue (MB) and tetracycline (TC) from
aqueous solution. In addition, the modified BVO/rGO films were prepared on a FTO substrate for use as an
efficient photoanode by a drop-cast method to efficiently promote PEC water splitting performance of BVO
under visible light irradiation. The photocatalytic activity of TC and MB in BVO/rGO reached 100 % photo
degradation of MB and TC in 60 and 55 min visible light irradiation, respectively, which are almost two times
higher than that of BVO. The photocurrent onset potential of BVO/rGO films was negatively shifted by -0.2
V. Their photocurrent density was reached to 133 µA cm−2
at 0.8 V which is more than 6 times of 21 µA cm−2
with BVO. In comparison to pristine BVO, BVO/rGO electrodes provide 8.4 times higher photocurrent
density and 2.2 times longer electron life time and also show excellent stability and reusability after 2400 s.
Our results exhibited that BVO/rGO films minimized electron-hole pairs recombination, which expands the
light absorption range and increases specific reaction sites. All these improvements are because BVO in
BVO/rGO nanocomposite was fully covered by rGO films and also its reduced particle size, which can be
important keys in significant improvement of photocatalytic degradation and PEC water splitting.
Acknowledgement
Following are results of a study on the "Leaders in INdustry-university Cooperation +" Project, supported by
the Ministry of Education and National Research Foundation of Korea.
139
P27: Suppressing Thermal Transport in Chain-Oriented Conducting Polymers for
Enhanced Thermoelectric Efficiency
Dong Wang1, Wen Shi
1, and Zhigang Shuai
1,2,3
1MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of
Chemistry, Tsinghua University, Beijing 100084, P. R. China 2Key Laboratory of Organic solids, Beijing National Laboratory for Molecular Sciences (BNLMS),
Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China 3Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University, Xiamen
351005, P. R. China
E-mail: [email protected]
High-performance thermoelectric materials should be excellent electrical conductors and poor heat
conductors. However, increased chain orientation of conducting polymers not only increases the electrical
conductivity, but also the lattice thermal conductivity. By using molecular dynamics simulations, we
demonstrate that suppressing thermal transport in chain-oriented conducting polymers can be achieved by
tailoring their degree of polymerization, without degrading the electrical transport properties, so it can
effectively improve the thermoelectric efficiency.[1]
This is based on the separated length scales that charge
carriers and phonons travel along the polymer backbone. We show that by tuning the chain length and the
crystallinity of chain-oriented poly(3,4- ethylenedioxythiophene) (PEDOT) fibers, thermal transport along the
polymer backbone can be significantly suppressed. For example, the axial thermal conductivity is decreased
from 41.7 W m−1 K
−1 in “ideal” crystalline polymers to 0.97 W m
−1 K
−1 in rationally designed polymer fibers
with the crystallinity of 0.49 and the relative molecular weight of 5600. As a consequence, the dimensionless
thermoelectric figure of merit at 298 K is enhanced to 0.48, which is approximately one order of magnitude
higher than that in crystalline polymers. Our results highlight alternative strategies to doping optimization for
achieving high thermoelectric efficiency in conducting polymers.
Figure 1. Enhancing thermoelectric figure of merit in the chain-oriented PEDOT fibres by suppressing thermal
transport via controlling the degree of polymerization and the crystallinity.
[1] W. Shi, Z. Shuai, D. Wang, Adv. Funct. Mater. 2017, 27, 1702847.
140
P28: Non-Ideal Behavior in Organic Field-Effect Transistors Induced by Charge
Trapping at the Interface
Hio-Ieng Un1, Jie-Yu Wang
1, and Jian Pei
1
1 College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China E-mail: [email protected]
Organic field-effect transistors (OFETs) with impressively high hole mobilities over 10 cm2 V-1 s-1 and
electron mobilities over 1 cm2 V-1 s-1 have been reported in the past few years.[1,2] However, significant non-
ideal transistor characteristics (e.g. voltage-dependent mobilities) have been widely observed in both small
molecule[3] and polymer[1,2] FETs. This issue makes the accurate evaluation of the electrical performance
impossible, and also limited the practical applications of OFETs.
Herein, for the first time, we report non-ideal behaviors in OFETs caused by semiconductor- unrelated
charge trapping. We directly observe the charge trapping and investigate its kinetic behaviors using scanning
Kelvin probe microscopy (SKPM). Our results reveal that both positive and negative charges can be trapped
in the absence of the semiconductor layer, and it occurs in a wide range of dielectrics with different
electrochemically active functional groups. More importantly, this semiconductor-unrelated charge trapping is
proved to generally appear in various p- and n-type small molecule and polymer transistors with diverse types
of dielectric materials (inorganic and organic) containing different functional groups (OH, NH2, COOH etc.).
Our study provides a new insight into the fundamental aspect of charge trapping and non-ideal characteristics
of OFETs, and also provides guidelines for device engineering towards ideal OFETs.
Figure 1. Schematic diagrams of the trapping-induced non-ideal behaviors in organic field-effect transistors.
[1] H.-R. Tseng, H. Phan, C. Luo, M. Wang, L. A. Perez, S. N. Patel, L. Ying, E. J. Kramer, T.-Q. Nguyen,
G. C. Bazan, A. J. Heeger, Adv. Mater., 2014, 26, 2993-2998.
[2] Y.-Q. Zheng, T. Lei, J.-H. Dou, X. Xia, J.-Y. Wang, C.-J. Liu, J. Pei, Adv. Mater., 2016, 28, 7213-7219.
[3] Y. Yuan, G. Giri, A. L. Ayzner, A. P. Zoombelt, S. C. B. Mannsfeld, J. Chen, D. Nordlund, M. F.
Toney, J. Huang, Z. Bao, Nat. Commun., 2014, 5, 3005.
P
P
P29: First-Principles Study on Thermoelectric Performance of
Graphene/Ferroelectric PVDF Hybrid Organic Materials
Hikaru Horii1, Yutaro Fujisaki2, Masahiro Ito1, Yoichiro Hasizume2, Takashi Nakajima2, Satoru Konabe1, Takahiro Yamamoto1
1Faculty of Engineering, Tokyo University of Science, Tokyo 125-8585, Japan 2 Faculty of Science, Tokyo University of Science, Tokyo 125-8585, Japan
E-mail: [email protected]
Thermoelectric conversion is a key technology for realizing IoT (Internet of Things) society, and
materials for such applications need flexibility and high performance. For obtaining high thermoelectric
performance, it is required that both the electrical conductivity and the Seebeck coefficient are high.
Currently, graphene has attracted attention as a potential flexible material for exhibiting such
performance. It is, however, necessary to dope carriers into graphene since both the electrical
conductivity and the Seebeck coefficient are zero without carrier doping. Moreover, thermoelectric
performance has an optimum value for a carrier density due to the trade-off relation between the
conductivity and the Seebeck coefficient. As carrier injection methods, the chemical doping is difficult
to finely control the carrier density and also reduces the mobility of graphene, while the electric field
doping uses an external electric source, which is not suitable for the application to the energy harvesting.
We thus propose a new carrier injection method using
the spontaneous polarization of ferroelectric materials,
which does not need an external electric source. To
validate this new method, we theoretically analyze the
carrier injection to graphene by the spontaneous
polarization of Polyvinylidene Fluoride (PVDF) using the
first-principles calculation based on the density functional
theory. The calculation models are shown in Figure 1.
Our calculation shows that electrons (holes) are
injected into up to the third layer of multilayer graphene
from the interface when multilayer graphene contacts a
surface of positive (negative) polarization of PVDF.
Therefore, it is expected that the thermoelectric properties
of graphene can be controlled by injecting carriers using
the polarization of PVDF.
We then performed an experiment using the ZEM-2
and observed that the conductivity and the Seebeck
coefficient of graphene/PVDF changed for positively or negatively polarized PVDF, compared with
that of the depolarization state. Furthermore, we found that the power factor of a hole-doped monolayer
graphene becomes 1.59 times larger than that of the undoped graphene. This result shows that carriers
were indeed injected and indicates that we can control the thermoelectric performance by the
spontaneous polarization of PVDF.
It is then necessary to optimize a carrier density to improve thermoelectric performance of graphene.
The optimum value of the carrier density in graphene is known as approximately 1012 cm-2 [1]. On the
other hand, a carrier density of 7×1013 cm-2 was injected in our calculation. Therefore, it is possible to
optimize thermoelectric performance using the spontaneous polarization because more carriers were
injected than the optimal density of graphene.
[1] E. H. Hwang et al., Phys. Rev. B 2009, 80, 235415.
(a) Positive (b) Negative Figure 1. Two simulation models. White,
black, and green indicate hydrogen, carbon,
and fluorine, respectively.
141
142
P30: Heat-sink-free Flexible Organic Thermoelectric Generator Vertically
Operating with Chevron Structure
Daegun Kim, Duckhyun Ju and Kilwon Cho
Department of Chemical Engineering, Pohang University of Science and Technology Pohang, 37673,
Korea
E-mail: [email protected]
Organic thermoelectric (TE) materials receive increasing attention as a key material for realizing a
flexible TE generator, which is applicable in versatile applications such as self-powered electronic- skin
and sustainable power source. A great advance to organic TE materials has been achieved for a decade
in terms of TE figure-of-merit, which is now comparable to that of bulk inorganic TE material. However,
organic-based TE generator is still limited to laboratory because it has failed to meet the practical
requirement; the operation in response to a vertical heat flow without a heat sink. We present herein a
flexible organic TE generator by introducing an optimized solution process, the chevron device structure,
and a foam medium. Electro-sprayed poly(3,4-ethylenedioxythiophene): polystyrene sulfonate
(PEDOT:PSS) possessed a distinctive film morphology, which leads to a high power factor (642 µW m-1
K-2
) and a low sheet resistance (< 10 Ω sq-1
) with optimized solvent post-treatment.
Chevron-structured TE generator that induces the in-plane charge transport for a vertical heat flow
generated a remarkable TE output (~ 1 µW at ΔT = 17.5 K) and had the mechanical flexibility. In
addition, the internal medium of the device enabled the heat-sink-free operation, which retains 70 % of its
maximum voltage output in the absence of a heat sink. Our work provides guideline for the fabrication of
flexible TE generator and contributes to the development of environment-friendly and sustainable power
source.
SPECIAL LECTURES
145
S1: Measurement System for Thermophysical Properties of
Thin Films in a Broad Temperature Range
H-W. Marx1, V. Linseis
2
1Linseis Messgeräte GmbH - Selb (Germany),
2Universität Hamburg - Hamburg (Germany).
E-mail: [email protected]
Due to new research efforts in the field of thermoelectrics with a focus on size effects, there is a growing
need for measurement setups dedicated to analyze thin films and nanowires with considerably different
physical properties than bulk material. The characterization of these samples is important to learn more about
their structure and conduction mechanism but also important for technical applications e.g. in the
semiconductor industry.
We report on the development of a new system to simultaneous measure the electrical and thermal
conductivity, the Seebeck Coefficient and the Hall Constant of a thin film sample in the temperature range
from liquid nitrogen up to 300°C. Due to the nearly simultaneous measurement at only one sample, errors
caused by different sample compositions, different sample geometries (thickness) and different heat profiles
can be avoided.
The system consists of two main parts, a structured Si-wafer and a suitable measurement setup. To measure
the el. conductivity and the Hall constant, the wafer owns a structure with four electrodes to use the Van-der-
Pauw method. For the Seebeck measurement an additional temperature gradient can be applied on a
membrane setup. The temperatures for the Seebeck calculation are measured with resistance thermometers on
the chip. The thermal conductivity can be measured in plane using the Völklein Method, doing a steady state
or transient measurement. Therefore a small heating/sensing stripe is deposited on a very thin nitride
membrane. The sample can be deposited directly on this membrane by various techniques. To get a correct
result, the measurement has to be done under vacuum in a thermal controlled chamber.
In order to meet these requirements a suitable vacuum chamber with sample holder and necessary ports has
been designed. The sample holder can be cooled with liquid nitrogen and heated by joule heating to create
either a constant temperature or a defined temperature gradient. To measure the Hall constant, the chamber is
put between two spools of an electromagnet to apply a variable magnetic field with a maximum of 1 T. As
proof of concept, a showcase study of Bi87Sb13 thin films in varying thickness has been performed and
compared to previously published data [1].
[1] Linseis, V., Völklein, F., Reith, H., Woias, P. and Nielsch, K.; (2016) Platform for in-plane ZT
measurement and Hall coefficient determination of thin films in a temperature range from 120 K up to 450 K,
Journal of Materials Research, 31(20), pp. 3196-3204. doi: 10.1557/jmr.2016.353.
146
S2: Thermoelectrics Based on Organic and Hybrid Materials
Stephen Shevlin1 and Olga Bubnova
2
1 Associate Editor, Nature Materials
Associate Editor, Nature Communications
E-mail: [email protected], [email protected]
In this presentation a brief guide to Nature journals is given. This includes a discussion of the history, what
makes a Nature paper, and the family of Nature journals. Moreover, a brief guide to the submission and
review process will be given, illustrating what we look for, how we deal with referee reports, and how
decisions are made.
147
AUTHORS INDEX
Abad, Libertad: B14 (p. 95), P24 (p. 136)
Abargues, Rafael: B2 (p. 83)
Abdalla, Hassan: B13 (p.94)
Agrait, Nicolás: I17 (p. 51)
Anno, Hiroaki: B20 (p. 101), B21 (p. 102)
Aslan, Silas: A1 (p. 55)
Bharti, Meetu: B26 (p. 107)
Bilotti, Emiliano: A16 (p. 70)
Biniek, Laure: I14 (p.48)Blackburn, Jeffrey: I3 (p. 37)
Bubnova, Olga: S2 (p. 144)Burton, M.: P22 (p. 134)
Campoy Quiles, Mariano: I12 (p. 46), A15 (p. 69), A27 (p. 80), B19 (p. 100), P11 (p. 123), P15 (p.
127)
Cantarero, Andrés: A17 (p. 71), B2 (p. 83), B6 (p. 87), P20 (p. 132), P21 (p. 133)
Carsí, Marta: P20 (p. 132), P21 (p. 133)
Cassinelli, Marco: A27 (p. 80), P19 (p. 130)
Chabinyc, Michael L.: PL2 (p. 29)
Chen, Yanling: B25 (p. 105)
Crispin, Xavier: A2 (p. 56), A4 (p. 58), A8 (p. 62), B5 (p. 86), P7 (p. 119)
Culebras, Mario: A17 (p. 71), B6 (p. 87), P20 (p. 132), P21 (p. 133)
d'Agosta, Roberto: B10 (p. 91)
Dalkiranis, Gustavo G.: B14 (p. 95), P24 (p.136)
Di, Chong-an: I10 (p. 44), I13 (p. 47), A26 (p. 79), B12 (p. 93),
Dörling, Bernhard: A15 (p. 69), B19 (p. 100), P11 (p. 123)
Du, Yong: A21 (p. 74), A24 (p. 77)
Fabiano, Simone: I11 (p. 45), A2 (p. 56), B5 (p. 86), B13 (p. 94), P7 (p. 119)
Fenwick, Oliver James: A7 (p. 61), P22 (p. 134)
Francisco López, Adrián: A27 (p. 80), P15 (p. 127)Fujigaya, Tsuyohiko: B3 (p. 84)
Fujisaki, Yutaro: P3 (p. 115)
García-Cañadas, Jorge: A10 (p. 64)
Gómez, Clara M.: A17 (p. 71), B2 (p. 83), B6 (p. 87), P20 (p. 132), P21 (p. 133)
Goñi, Alejandro: I12 (p. 46), A27 (p. 80), P15 (p. 127)
Grunlan, Jaime C.: PL1 (p. 29), P8 (p. 120)
Han, Shaobo: A2 (p. 56)
Hashizume, Yoichiro: P3 (p. 115), P5 (p. 117), P12 (p. 124)
Hikaru, Horii: P3 (p. 115), P29 (p.141)Horike, Shohei: B7 (p. 88)
Imae, Ichiro: P6 (p. 118)
Ito, Masahiro: B20 (p. 101), P3 (p. 115), P12 (p. 124)
Jang, Jaegyu: A11 (p. 65)
Jeandupeux, Laure: A20 (p. 73),
Jiao, Fei: A2 (p. 56), A8 (p. 62)
Jurado, Jos‚ Piers: B19 (p. 100)
Kanahashi, Kaito: A24 (p. 77), A25 (p. 78),
Kandhasamy, Sathiyaraj: B15 (p. 96)
Katz, Howard: I9 (p. 43)
Kawai, Tsuyoshi: I2 (p. 36), B8 (p. 89), B9 (p. 90)
Kemerink, Martijn: I7 (p. 41), B13 (p. 94),
Keppner, Herbert: A20 (p. 73)
Kim, Daegun: P30 (p.142),
Kiyota, Yasuhiro: B17 (p. 98)
Kojima, Hirotaka: B16 (p. 97), P23 (p. 135)
Krahl, Fabian: A6 (p. 61)
148
Kroon, Renee: A13 (p. 67)
Kumar, Pawan: A9 (p. 63)
Kwak, Jeonghun: P13 (p. 125), P16 (p. 128)
Laure, Biniek: I18 (p. 52)
Laux, Edith: A20 (p. 73)
Lee, Byeong-Kyu: P26 (p. 138)
Lee, Chang-Soo: P18 (p. 130)
Liang, Ziqi: B11 (p. 92)
Liu, Yunpeng: P25 (p. 137)
López, Adrián F.: A27 (p. 80), P15 (p. 127)
Lu, Yang: P1 (p. 113)
Marin, Giovanni: B22 (p. 103)
Marx, Hans-W.: S1 (p. 144)
Massetti, Matteo: A28 (p. 81), P19 (p. 131)
Matsushita, Stephane Yu:
Menon, Akanksha K.: A22 (p. 75)
Miyazaki, Koji: A3 (p. 57)
Mori, Takao: A19 (p. 72)
Müller, Christian: I6 (p. 40), A13 (p. 67)
Muñoz-Espí, Rafael: A17 (p. 71), P21 (p. 133)
Murata, Michihisa: P9 (p. 121)
Nakajima, Takashi: B20 (p. 101), P3 (p. 115), P5 (p. 117) , P12 (p. 124)
Nakano, Motohiro: B8 (p. 89),
Nonoguchi, Yoshiyuki: B8 (p. 89), B9 (p. 90),
Park, Juhyung: P13 (p. 125), P16 (p. 128),
Pei, Jian: A26 (p. 79), B27 (p. 108), P1 (p. 113)
Pflaum, Jens: I4 (p. 38)
Prunet, Geoffrey: P17 (p. 129),
Pudzs, Kaspars: B23 (p. 104), B24 (p. 105)
Qu, Sanyin: A25 (p. 78), B25 (p. 106)
Rösch, Andres: B18 (p. 99),
Rutkis, Martins: B23 (p. 104), B24 (p. 105)
Sanchis, Maria J.: A17 (p. 71), P20 (p. 132), P21 (p. 133)
Seijas, Álvaro: B2 (p. 83), P20 (p. 132)
Serrano-Claumarchirant, José F.: A17 (p. 71), P20 (p. 132), P21 (p. 133)
Schroeder, Bob C.: A16 (p. 70)
Segalman, Rachel A.: I1 (p. 35)
Selezneva, Ekaterina: A5 (p. 59)
Shevlin, Stephen: S2 (p. 145)
Shuai, Zhigang: I8 (p. 42), P25 (p. 137), P27 (p. 139)
Statz, Martin: I5 (p. 39), P4 (p. 116)
Tkachov, Roman: B28 (p. 109)
Toshima, Noaki: PL3 (p. 31)
Toyama, Nana: P9 (p. 121)
Un, Hio-Ieng: P28 (p. 141)
Virgil, Andrei: A14 (p. 68)
Wan, Kening: A16 (p. 70)
Wang, Dong: I8 (p. 42), P25 (p. 137), P27 (p. 139)
Whittaker-Brooks, Luisa: B1 (p. 82)
Wijeratne, Kosala: A4 (p.58),
Xu, Ling: B27 (p. 108), P2 (p. 114)
Xu, Wei: I13 (p. 47), A12 (p. 66)
Yamamoto, Takahiro: B20 (p. 101), P3 (p. 115), P5 (p. 117), P12 (p.
124) Yan, Hu: A23 (p. 75)
147
Yang, Chi-Yuan: A26 (p. 78)
Yee, Shannon K.: I15 (p. 48), A22 (p. 74)
Yuan, Dafei: A12 (p. 65), B12 (p. 92)
Zapata-Arteaga, Osnat: A15 (p. 68), B19 (p. 99)
Zhao, Dan: B5 (p. 85), A8 (p. 61)
Zhu, Daoben: I10 (p. 43), I13 (p. 46), A12 (p. 65), B12 (p. 92)
Zhu, Xiaozhang: A12 (p. 65), B12 (p. 92)
Zotti, Linda A.: I16 (p. 49)
