Ultrahigh-efficiency solar cells based on nanophotonic design

Transcription

1 Ultrahigh-efficiency solar cells based on nanophotonic design Albert Polman Piero Spinelli Jorik van de Groep Claire van Lare Bonna Newman Erik Garnett Marc Verschuuren Ruud Schropp Wim Sinke Center for Nanophotonics FOM-Institute AMOLF Amsterdam, The Netherlands Dhritiman Gupta Martijn Wienk Rene Janssen Patrick de Jager Michel van de Moosdijk Guanchao Yin Martina Schmid Vivian Ferry Emily Kosten Harry Atwater

2 Solar spectrum and Shockley-Queisser limit I ext = I 0 exp(v/kt)-i SC

3 Record efficiencies of solar cell materials GaInP

4 Strategies towards high efficiency at low costs 1) Wafer-based Si solar cells ( 25-29%) Reduce costs (=reduce wafer thickness: µm) Decrease recombination at surface, junctions, contacts Increase light trapping, angular emission restriction,.. 2) Thin-film solar cells Increase efficiency & reduce costs 3) Dual-junction solar cells on silicon ( 30-35%) Increase efficiency and bandgap of top cells Define spectral splitting architectures 4) New materials and designs ( >40%) Novel multijunction cell architectures Nanowire solar cells.

5 Light coupling and trapping by resonant light scatterers H.A. Atwater and A. Polman Nature Mater. 9, 205 (2010)

6 Absorption length in silicon 100 µm 10 µm physics.ucsd.edu japantechniche.com, pvlab.epfl.edu

7 Light coupling and trapping by resonant light scatterers 4% n=1.0 n=3.5 96% H.A. Atwater and A. Polman Nature Mater. 9, 205 (2010)

8 Silicon Mie scatterer on a Si substrate Si sphere Si cylinder Si Mie resonance Si Si Silicon nano-cylinders act as cavities for light and direct light into the substrate Si Piero Spinelli Nature Comm. 3, 692 (2012)

9 Electric and magnetic Mie modes MD Q sca t Si 100 nm 100 nm ED Jorik van de Groep Optics Express 21, (2013)

10 Black silicon using leaky Mie resonances Average reflectivity: 1.3% Si3N4 Si Si Piero Spinelli Nature Comm. 3, 692 (2012)

11 Substrate conformal imprint lithography PDMS Stamp Thin glass PDMS stamp (6 ) on 200 µm AF-45 glass 1 µm Full-wafer soft nano-imprint Flexible rubber on thin glass Conform to substrate bow and roughness No stamp damage due to particles Marc Verschuuren PhD thesis, Utrecht University (2010)

12 Light coupling and trapping by resonant light scatterers H.A. Atwater and A. Polman Nature Mater. 9, 205 (2010)

13 Light trapping in 5 µm crystalline Si slab Goal: higher V OC (reduced bulk recombination) 100 FDTD simulation Mie (random) Absorption (%) Mie (periodic) flat coating Wavelength (nm) Enables 20 µm thick Si solar cell with efficiency > 23 % Piero Spinelli J. Photovolt. 4, 554 (2014)

14 Ultra-thin a-si:h solar cell: 90 nm i layer 400 nm pitch Experiment patterned flat enhanced red and blue response by resonant dielectric Simulation scatterers 400 nm pitch 400 nm pitch flat flat 500 nm pitch 500 nm pitch 500 nm" ITO" a-si:h" ZnO:Al" Ag" sol-gel" The solar cell as an optical integrated circuit Vivian Ferry, Claire van Lare Nano Lett. 11, 4239 (2011), Optics Express 21, (2013)

15 Thin-film solar cells are optical waveguides 0 k = ω n c air TM0 Energy (ev) k 0 (rad/µm) Si H y (a.u.) TM1 k = 2π λ TM2 k waveguide (rad/µm) Air ITO asi ZnO Ag Claire van Lare

16 Thin-film solar cells are optical waveguides k 0 (rad/µm) 550 nm Spectral range where light trapping is required 800 nm k wg =k o sin(ϕ)+nk gr k waveguide (rad/µm) Claire van Lare

17 Thin-film solar cells are optical waveguides k 0 (rad/µm) 550 nm k wg =k o sin(ϕ)+nk gr Desired spatial frequencies in scattering pattern 800 nm k waveguide (rad/µm) Claire van Lare

18 Optimizing spatial frequency of scattering pattern Asahi U-type Claire van Lare

19 Light coupling and trapping by resonant light scatterers 4% n=1.0 n=3.5 96% H.A. Atwater and A. Polman Nature Mater. 9, 205 (2010)

20 Ag nanoparticle anti-reflection coating on Si Ag nanoparticles on Si wafer Reflectivity data nanoparticles made with soft-imprint Piero Spinelli Nano Lett. 11, 1760 (2011)

21 Transparent conductive silver nanowire network 2 µm Ag nanowire network fabricated with electron beam lithography width: nm height: 60 nm Jorik van de Groep, Piero Spinelli Nano Lett. 12, 3138 (2012)

22 Transparent conductive silver nanowire network Optical transmission 45 nm 110 nm MIM plasmons Localized plasmons Surface plasmons I-V Equal to ITO Jorik van de Groep, Piero Spinelli Nano Lett. 12, 3138 (2012)

23 Spectral response of polymer cells with Ag networks glass ITO PEDOT 3HT:PCBM glass PEDOT 3HT:PCBM Al EQE nanowires ITO ITO device Nanowire device Al TE Wavelength [nm] Jorik van de Groep, Dhritiman Gupta

24 Nanopatterned thin (460 nm) CIGSe cells experiment simulation Claire van Lare, Guanchao Yin

25 Nano-glass 10 Reflection (%) Bare glass (R = 7.69%) 1-side (R = 4.45%) 2-side (R = 0.96%) PDMS Stamp Thin glass Wavelength (nm) PDMS stamp (6 ) on 200 µm AF-45 glass Piero Spinelli, Jorik van de Groep

26 Enhanced light trapping by limiting emission angle max: 4n 2 10 µm max: >4n 2 Appl. Phys. Lett. 99, (2011) A. Polman and H.A. Atwater, Nature Mater. 11, 174 (2012)

27 Scalable inexpensive large-area layer transfer and nanofabrication techniques A. Polman and H.A. Atwater Nature Mater. 11, 174 (2012)

28 Roadmap nanopatterning for photovoltaics Bonna Newman

29 Thank you