PHOTONIC ENHANCED SOLAR CELLS - Sites FCT/UNL · Manuel J. Mendes ([email protected]) – AltaLuz Kick-Off meeting, CENIMAT-UNINOVA Portrait of Light trapping regimes 16 Cone-like

PHOTONIC‐ENHANCED SOLAR CELLS WITH PLASMONIC AND

WAVE‐‐‐‐OPTICAL DIELECTRIC NANOSTRUCTURES

M. J. MENDES, O. SANCHEZ, A. ARAÚJO, A. VICENTE, A. LYUBCHYK, T.

MATEUS, H. ÁGUAS, E. FORTUNATO AND R. MARTINS

i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa and CEMOP/UNINOVA, Campus de Caparica, 2829-516 Caparica, Portugal.

AltaLuz - KickOff

31 May 2016

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Manuel J. Mendes ([email protected]) – AltaLuz Kick-Off meeting, CENIMAT-UNINOVA

Trends in Photovoltaics

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2 Light Trapping Approaches Developed

1. Plasmonic back reflectors with Ag nanoparticles arrays

2. High-index dielectric front structures with wavelenght-sized spheroids

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Approach 1 - Plasmonics 4


Plasmonic Back Reflectors (PBRs) 5

Mie Theory Analysis:

M. J. Mendes et al. Nanoscale 6, 4796-4805 (2014)


Plasmonic Back Reflectors in CENIMAT

S. Morawiec, M. J. Mendes et al. Optics Express (2014)

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Enhancement of:

� 22.3% for total Jsc

� 62.5% for Jsc within 600-800 nm range (NIR)



S. Morawiec, M. J. Mendes et al. Optics Express (2014)

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Enhancement of:


� 62.5% for Jsc within 600-800

nm range (NIR)



Enhancement of:


� 62.5% for Jsc within 600-800 nm range (NIR)

� 25.2% for cell efficiency

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Novel Colloidal Plasmonic Nanostructures 9

www.bbisolutions.com

Plasmonics = resonant effect → the amazing scattering properties can only be fully exploited with highly monodisperse nanostructures in terms of metal NPs geometry and spacing

Au

Au

Au

M. J. Mendes et al. Nanoscale, 6 (2014)


Application in thin film Si solar cells 10

M. J. Mendes et al. Nanotechnology, 26 p. 135202 (2015)


PBRs on the rear of thin film Si cells 11


Response of Plasmonic-enhanced solar cells 12

JSC

(mA/cm2)

JSC 600-800 nm

(mA/cm2) Voc (V) FF

Flat BR (Reference) 9.34 2.25 0.54 0.48

Textured Asahi BR 12.8 3.99 0.53 0.49

PBR 100 nm NPs 11.8 3.21 0.55 0.51

PBR 150 nm NPs 13.3 4.06 0.53 0.50

PBR 200 nm NPs 13.1 3.82 0.54 0.48

M. J. Mendes et al. Nanotechnology, 26 p. 135202 (2015)

Approach 2 – Wave optics 13


Advantages of Dielectric Mesoscopic Particles 14

� Best scatterers: High-index dielectric wavelength-sized particles

� Best location: on front TCO contact

o Why?

� Pronounced scattering cross sections without the associated parasitic absorption of MNPs

� Suppress reflection - efficient broadband ARCs

� Adaptable forward scattered near-field which can focus light in distinct types of thin PV layers

� Increase angular acceptance (compared with ARCs)


Principles for numerical optimization 15

� Planar absorber layer – LT structures should not increase the surface area of the photocurrent-generating layer, to prevent the increase of recombination in the cell

Maximization of absorption in Si determined with Lumerical FDTD. Figure of merit = JSC

M. J. Mendes et al. Nano Energy (2016)


Portrait of Light trapping regimes 16

Cone-like shape → index-matching with high-index Si layer

Multiple reflections of light with long penetration depth → Fabry-Perot interference

Forward-scattered near-field → light focusing in the thin layer

Strong scattering cross-sections → path lenght

enhancement and confined waveguided

modes



Optimal AZO ARC – Anti-reflection alone 17



Optimization of Dielectric Spheroids 18



Optimization of Half-Spheroids 19



Predicted JSC enhancement relative to ARC 20

Next step: Fabrication

Lambertian limits (geometric optics):


Colloidal Lithography 21

Step 1: Deposition of ~1 µm spheres in close-packed array

Step 2: Modification of shape and distance with dry-etching (RIE)

Step 3: Infiltration of TiO2 deposited with Sputtering

Step 4: Spheres removal (lift-off)


Step 1 : Close-Packed Arrays of PS Spheres 22

Particles: 1 µm Polystyrene colloidal spheres Methodologies tested: Rod-Coating and Langmuir-Blodgett


Step 2 : Shaping colloidal mask with RIE 23

No etching 120 s RIE 160 s RIE


Step 3 : Infiltration of TiO2 24


Step 4 : Litf-off of Spheres (mask) 25

Structures height: 500-600 nm

Spacing ~ 1 µm


Conclusions 26

� Colloidal Plasmonic Back Reflectors have high monodisperse MNPs and provide high enhancement in NIR

� However, Plasmonics has unavoidable drawbacks in PV: � Parasitic absorption

� Rear-located NPs increase surface area (roughness) of the cell

� High-index dielectric wavelength-sized structures can circumvent such issues and offer additional advantages: � Broadband light trapping due to combination of different effects

� Cheaper materials – lower costs

� More adaptable to different types of thin film solar cells

Thank you! 27

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FUNDING:

EU FP7 Marie Curie Action (FP7- PEOPLE-2013-IEF) - DIELECTRIC PV project (Grant No. 629370) FEDER funds (COMPETE 2020 Program) and Foundation for Science and Technology (FCT-MEC) - PTDC/CTM-ENE/5125/2014, UID/CTM/50025/2013, PEst-C/CTM/LA0025/2013-14 and PTDC/ CTM-ENE/2514/2012.

Extra slides 28


� Mie theory:

~10% coverage is sufficient for full light interaction

Control of particle density on the surface 29

Surface coverage:

~5%

~8%


From Dipolar to Wavelength size 30

Pa

rtic

le S

ize

(Req)

Electrostatic/Dipolar Regime

Transition Regime

Mesoscopic Regime

M. J. Mendes et al. Optics Express (2011)

Documents

PHOTONIC ENHANCED SOLAR CELLS - Sites FCT/UNL · Manuel J. Mendes ([email protected]) – AltaLuz Kick-Off meeting, CENIMAT-UNINOVA Portrait of Light trapping regimes 16 Cone-like