Renewable Energy

Based on solar and wind…• Intermittent• Uncontrollable• Localized

Electrical Energy Storage

“Achilles’s heel of renewable energy”• Balance generation and demand

• Improve power reliability & economy• Critical for renewable energy

penetration

Smart Grid & Applications

Electricity Distribution & Efficient UsageImprove power economy through

• Digital balancing of demand & supply• Solid State Lighting

• Low power computation

POLICY

Intimate and Mutually Dependent Relationship Between Electrical Energy Generation, Storage, Distribution, and Efficient Uses

JACS, 2009 (DOI: 10.102 / ja9066139)Chem. Mater., 2009, 21, 2598.

Adv. Func. Mater., 2009, 19, 2457.

New Design Concept for Low Bandgap PV Polymers : D--A Side Chain Polymers for High Performance Solar Cells

• Facile tuning of energy levels and band gaps• HOMO level mainly depends on polymer backbone• LUMO levels tuned by acceptors

D1 D2 D1 D2

A

Brid

geD1

A

Brid

ge

New Design Concept Conventional D-A Polymers

Eg.

Increasing acceptor strength

Huang, Yip & Jen, J. Am. Chem. Soc., 2009, (DOI: 10.102 / ja9066139)

N

C8H17C8H17

n

CN

NC

NN

O

O

S

O

NC

CN

R=

S

R

HOMO(eV)

LUMO(eV)

Bandgap

PF-DCN -5.45 -3.55 1.90

PF-PDT -5.45 -3.7 1.75

PF-DCNIO -5.45 -3.9 1.55

PCBM -6.0 -4.3 1.7

Optical Properties and Energy Levels for the New Polymers

PF-DCN PF-PDT PF-DCNIO

Thin film absorption spectrum

Data from CV and UV-Vis absorption study

Potential PCE

N

C8H17C8H17

n

CN

NCN

N

O

O

S

O

NC

CN

R=

S

R

FET performan

ce

Hole mobility

(cm2 V-1s-1)OPV performance

VOC (V)

JSC

(mA/cm-2)FF PCE

(%)

PF-DCN 1.16E-04 PF-DCN:PC71BM 0.98 9.45 0.49 4.57

PF-PDT 5.18E-04 PF-PDT:PC71BM 0.98 9.42 0.46 4.27

PF-DCNIO 6.70E-04 PF-DCNIO:PC71BM 0.93 7.93 0.47 3.47

OPV configuration : ITO/polymer:PC71BM w:w = 1:4 (80nm)/Ca/Al

Performance of Bulk Heterojunction Polymer Solar Cells

-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2

-10

-8

-6

-4

-2

0

2

4

6

Cur

rent

den

sity

(m

A/c

m2 )

Voltage (V)

PF-DCN:PC71

BM

PF-PDT:PC71

BM

PF-DCNIO:PC71

BM

400 450 500 550 600 650 700 750 8000

20

40

60

80

100

EQ

E (

%)

Wavelength (nm)

PF-DCN:PC71

BM

PF-PDT:PC71

BM

PF-DCNIO:PC71

BM

• Hole mobilities of 10-3 to 10-4 cm2/Vs in OFET• Low lying HOMO (5.45eV) resulted in high Voc of ~1V• All three polymers show promising OPV performance (as high as 4.8%)

Nanoscale phase-separated morphology in bulk heterojunction P3HT:PCBM film is not very thermodynamically stable

PCBM has certain freedom to diffuse slowly or re-crystallize over time especially under elevated temperatures

This is detrimental to the long-term morphological stability of OPVs

Manca J. et al., Adv. Funct. Mater. 16, 760 (2006)Chem. Commun. 17, 2116 (2003)

PCBM crystal

Morphological Stability of Polymer / PCBM Bulk Heterojucntions

• Develop amorphous fullerene derivatives to suppress crystallization• Replace phenylene ring in PCBM with bulky triphenylamine and dimethylfluorene

Thermally Stable Polymer Solar Cells Using Amorphous PCBM Acceptors

0 50 100 150 200 250 300

-4

-2

0

2

Heat flow

(uW

)

Temperature (oC)

PCBM PA-PCBM MF-PCBM

Tg =170C

Tg =180C

Crystallization

DSC

0 50 100 150 200 250 300

-4

-2

0

2

Heat flow

(uW

)

Temperature (oC)

PCBM PA-PCBM MF-PCBM

Tg =170C

Tg =180C

Crystallization

DSC

0 -500 -1000 -1500 -2000 -2500

-2

0

2

4

6

8

Cur

rent

Den

sity

(uA

)

V (vs Ag/Ag+, mV)

PCBM TPA-PCBM MF-PCBM

CV

No crystallization for new PCBMs Slightly decrease in LUMO for new PCBMs

Zhang, Yip & Jen, Chem. Mater., 2009, 21, 2598.

BHJ Morphological Stability Under 150°C Annealing

• Thermal annealing of P3HT:PCBMs films at 150°C for different times• PCBM crystals grow over time• No sign of crystallization for new PCBM derivatives after 10 hrs of annealing

200m

600 min

200m

600 min

P3HT : PCBMP3HT : TPA-PCBM

P3HT : MF-PCBM

Zhang, Yip & Jen, Chem. Mater., 2009, 21, 2598.

-0.2 0.0 0.2 0.4 0.6 0.8-12

-8

-4

0

4

Curr

ent d

ensi

ty (

mA

/cm

2 )

Voltage (V)

P3HT:PCBM 0 min 10 min 30 min 100 min 300 min 600 min

-0.2 0.0 0.2 0.4 0.6 0.8-12

-8

-4

0

4 P3HT:MF-PCBM 0 min 10 min 30 min 100 min 300 min 600 min

Curr

ent d

ensi

ty (

mA

/cm

2)

Voltage (V)

-0.2 0.0 0.2 0.4 0.6 0.8-12

-8

-4

0

4 P3HT:TPA-PCBM 0 min 10 min 30 min 100 min 300 min 600 min

Curr

ent d

ensi

ty (

mA

/cm

2 )

Voltage (V)

0 100 200 300 400 500 6000

1

2

3

4

5

P3HT:PCBM P3HT:PA-PCBM P3HT:MF-PCBM

PC

E (%

)

Annealing time (min)

• New PCBMs-based devices shown no degradation after long time annealing• Important strategy to improve longevity of polymer solar cells

OPV device performance with different annealing time

P3HT: PCBM

P3HT: MF-PCBM

P3HT: TPA-PCBM

Thermally Stable PSCs Using Amorphous PCBM Acceptors

Engineer Interface Using Functional SAMsEngineer Interface Using Functional SAMs

• Control charge coupling at interfaceControl charge coupling at interface

• Control upper layer growth Control upper layer growth mode and morphologymode and morphology

• Passivation of inorganic surface trapsPassivation of inorganic surface traps

• Molecular dipole controls Molecular dipole controls interfacial energy offsetinterfacial energy offset

ZnO/SAM/Metal Hybrid Cathode for High Performance OPVs

Cathode: Pure MetalCathode: Pure Metal

Yip & Jen, Adv. Mater., 2008, 20(12), 2376; APL, 2008, 92, 193314.

Flexible Polymer Inverted Solar Cells with Good Stability

Superior Inverted OPVs through Integrated Process

0.0 0.2 0.4 0.6-15

-10

-5

0

5

Cur

rent

Den

sity

(m

A/c

m2 )

Voltage (V)

ZnO NPs (No SAM) ZnO NPs (C60-SAM)

No SAM : ~3.8%With SAM : ~4.9%

0 4 8 12 16 20 24 28 32 36 40

0.0

0.2

0.4

0.6

0.8

1.0

Inverted structure Conventional strcuture

Nor

mal

ized

OP

V e

ffici

ency

Time (days)

Flexible solar cell with inverted structure

Hau, Yip & Jen, APL 2008, 92, 253301.

Unique device structure that supports all-printing fabrications

• ZnO provides higher mobility and a room temperature solution processible option compared to TiO2

• ZnO has similar electron trap states that need to be passivated to improve charge transfer at interface

Huang & Jen, J. Mater. Chem., Cover Page, 2008, 18, 4495. 15

PFN-OH has the following advantages:1) The fluorene conjugated backbone has better charge

transport ability;2) Alcohol-based solvents facilitate multilayer PLEDs fabrication; 3) The side chain groups significantly improve electron injection

from high work-function metals (Al, Ag and Au).

ITOGlass substrate

HTL

EML

ETL

Cathode

Neutral Conjugated Surfactants as Electron Injection Materials in OLEDs Neutral Conjugated Surfactants as Electron Injection Materials in OLEDs

Huang & Jen, Adv. Mater., 2007, 19(15), 2010.Zhang, Huang & Jen, Adv. Mater. 2008, 20, 1565.Huang & Jen, Adv. Mater., 2009, 21, 361.

Modified surfactant

EML (white)

ITO Glass

PEDOT (30nm)

Cathode

CIE (0.36, 0.38)

Device Performance (forward viewing)Max E.Q.E : 18.3 (%)L.E. : 46.6 (cd/A)P.E. : 29.1 (lm/W)Brightness : 19600 (cd/m2) at 15V

Device Performance (total viewing)L.E.: 61.4 (cd/A)P.E.: 49.5 (lm/W)--The best white PLED

Highly Efficient WPLEDs through Molecular Engineered Surfactants as Electron-Injecting & Transporting Materials

17

White Solid-state Lighting Developed in Jen Group

18

Binary and Ternary Materials with E-O activities Beyond theBinary and Ternary Materials with E-O activities Beyond the Saturation Limit of Common Poled Guest-Host PolymersSaturation Limit of Common Poled Guest-Host Polymers

Self-assembled HDFD series

0 10 20 30 40 50

Nor

mal

ized

r33

(a.

u.)

Active Chromophore wt%

Binary chromophores in a polymer

AJL8 in a polymer

AJ-TTE-II in a polymer

Binary chromophoreIn self-assembled HDFD

Ternary chromophores in a polymer

O

OO

O

O

O

O

O

F F

F

FF

F

FF

FF

Kim, Luo & Jen, J. Am. Chem. Soc., 2007, 129, 488. Zhou, Luo & Jen, Adv. Mater., 2009, 21(19), 1976.

Unprecedented E-O Activities Achieved Through Unprecedented E-O Activities Achieved Through Molecular Engineering and Integrated Center EffortsMolecular Engineering and Integrated Center Efforts

STC Developed E-O Materials

STC/MORPH

Goal20X better than the state-of-the-artinorganic, LiNbO3

Jen, Dalton, Robinson, Reid

Unprecedented Low Voltage (VUnprecedented Low Voltage (V) in Hybrid ) in Hybrid Polymer / Sol-gel E-O ModulatorsPolymer / Sol-gel E-O Modulators

Nature Photonics, 2007, 1, 180.Appl. Phys. Let., 2007, 91, 093505.IEEE Photon. Technol. Let., 2008, 20(12), 1051.

Combine low optical loss glass waveguide and high r33 EO polymer

0.38 V has been realized by Lumera0.38 V has been realized by Lumera

Packaged hybridAJ309 MZ modulator

2002 2003 2004 2005 2006 20070

10

20

30

40

50

60

70

80

Half W

ave V

olt

ag

e V

[V

]

Year

Y. Enami et al. JLT 21, 2053, 2003Y. Enami et al. APL 83, 4692, 2003Y. Enami et al. SPIE 5351, 28, 2004Y. Enami et al. APL 89, 143506, 2006Y. Enami et al Nature Photon, 1, 3, 180,2007unpblished

Two Order of Improvements in V Achieved in STC for Hybrid E-O Modulators

Norwood, Peyghambarian (UA), Luo, Jen (UW)

Back end integration of an “optical layer” w/CMOS enables:• High bandwidth• Low power• Long distance

A New CMOS Platform - On-Die Optical IOA New CMOS Platform - On-Die Optical IOPhotonics on top of CMOS Photonics on top of CMOS

chip

Optical Layer

chip

Optical Layer

Laser

Optical IO

specific modulators

Photodetector

Waveguide

CW Laser

Monolithic Integration

Optical Layer

Chip (CPU, Memory, Graphics, etc.)

filter

0011010101100101111001

10101010011

10011010110

0001110101010110101011

10011011001

10010010001

chip

Optical Layer

chip

Optical Layer

Laser

Optical IO

specific modulators

Photodetector

Waveguide

CW Laser

Monolithic Integration

Optical Layer

Chip (CPU, Memory, Graphics, etc.)

filter

0011010101100101111001

10101010011

10011010110

0001110101010110101011

10011011001

10010010001

-45

-43

-41

-39

-37

-35

-33

-31

-29

1314 1314.1 1314.2 1314.3 1314.4 1314.5 1314.6

Wavelength (nm)

Inen

sity

(dB

)

-20 V 20 V

Nor

mal

ized

Tra

nsm

issi

on (

dB) 0

-2

-4

-6

-8

-10

-12

-45

-43

-41

-39

-37

-35

-33

-31

-29

1314 1314.1 1314.2 1314.3 1314.4 1314.5 1314.6

Wavelength (nm)

Inen

sity

(dB

)

-20 V 20 V

-45

-43

-41

-39

-37

-35

-33

-31

-29

1314 1314.1 1314.2 1314.3 1314.4 1314.5 1314.6

Wavelength (nm)

Inen

sity

(dB

)

-20 V 20 V

Nor

mal

ized

Tra

nsm

issi

on (

dB) 0

-2

-4

-6

-8

-10

-12

10 GHz Modulation Speed Demonstrated

Block, Younkin, Chang (Intel), Jen (UW), Optics Express, 2008, 16(22), 18326

AA

silicon oxide

silicon nitride

copper

B

silicon oxide

silicon nitride

copper

B

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