Light management in nanostructured solar cells

Transcription

1 Light management in nanostructured solar cells Albert Polman Center for Nanophotonics FOM-Institute AMOLF Amsterdam, The Netherlands

2 Collaborators Piero Spinelli Jorik van de Groep Claire van Lare Vivian Ferry ECN Frank Lenzmann Wim Soppe AMOLF UU Ruud Schropp Philips Marc Verschuuren CALTECH Vivian Ferry Harry Atwater

3 Outline 4. Solving V oc < E g 1. Light coupling 2. Light trapping 3. Current collection 5. Towards 70% efficiency

4 The scattering solar cell Integrate nanoscatterers in the solar cell Couple incident light to in-plane waveguide modes or localized modes Nature Mater. 9, 205 (2010)

5 Light scattering from nanoparticles Large scattering cross section Strong forward scattering 4% air (n=1.0) Si (n=3.5) 96%

6 Light scattering from nanoparticles Large scattering cross section All light captured

7 Ag nanoparticles; scattering vs. Ohmic losses Albedo 1 for D > 150 nm Albedo Ag particle in air For Ag particles >150 nm nearly all light is scattered 50 nm For 50 nm particles 50% of the light is Absorption ~ r 3 Ag absorbed Scattering ~ r 6 in the metal

8 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)

9 Total reflectivity (specular+diffuse) Experimental data Piero Spinelli Nano Lett. 11, 1760 (2011)

10 Ag nanoparticle coated thin-film a-si cells 10% enhanced photocurrent 350 nm i-a-si:h 120 nm ZnO, 80 nm ITO Cell area: 0.13 cm 2 Ag particles: pitch 500 nm height 120 nm diameter 240 nm Claire van Lare, Wim Soppe

11 Transparent resonant conductive plasmonic networks 2 µm Ag wire network fabricated with e-beam lithography width: nm height: 60 nm Jorik van de Groep, Piero Spinelli

12 Optical transmission measurements Metal-insulator-metal plasmons Localized plasmons Surface plasmons Jorik van de Groep, Piero Spinelli

13 Optical transmission measurements ITO: Pitch: Thin wire networks are better than 80 nm ITO w=45 nm Jorik van de Groep, Piero Spinelli

14 Electrical resistance measurements w=45 nm Four-Point-Probe Ohmic behavior Jorik van de Groep, Piero Spinelli

15 Tradeoff between transmission and resistance Dilute network better than ITO Optimum for smallest w and small pitch Jorik van de Groep, Piero Spinelli

16 Combining light trapping and current collection Jorik van de Groep, Piero Spinelli

17 Metallic vs. dielectric scatterers 1 1 E 2 2 Q = scat C C scat geom 2 E 2 3 m Metal NP: plasmonic resonance 4 0R ε α = πε ε ε + 2εm Dielectric NP: Mie (geometrical) resonance Piero Spinelli

18 Si surface Mie scatterers sphere cylinder In cylindrical particles light leaks into the substrate and resonance broadens Nature Comm. 3, 692 (2010)

19 nm Si Light incoupling using Si nanoparticle array Weakly coupled Mie scatterers nm Near-perfect anti-reflection coating! Si Si 3 N 4 Si radius = 125 nm height = 150 nm pitch = 450 nm Si 3 N 4 thickness = 45 nm Piero Spinelli Nature Comm. 3, 692 (2012)

20 Black silicon using leaky Mie resonances Average reflectivity: 1.3% Si Si 3 N 4 Si Piero Spinelli Nature Comm. 3, 692 (2012)

21 The scattering solar cell Integrate nanoscatterers in the solar cell Couple incident light to in-plane waveguide modes or localized modes Nature Mater. 9, 205 (2010)

22 Back contact nanopatterns on ultrathin a-si:h solar cells 500 nm ITO a-si:h ZnO:Al Ag sol-gel nm thick a-si:h cells Vivian Ferry, Claire van Lare Nano Lett. 11, 4239 (2011)

23 Ultra-thin Si solar cell: 90 nm i layer light enhanced red and blue response Experiment blue Simulation 400 nm pitch Asahi 400 nm 400 nm pitch pitch 500 nm 500 nm pitch pitch flat flat flat random red Vivian Ferry, Claire van Lare Nano Lett. 11, 4239 (2011)

24 Outline 4. Solving V oc < E g 1. Light coupling 2. Light trapping 3. Current collection 5. Towards 70% efficiency

25 Thermodynamic energy losses in PV energy conversion Nature Mater. 11, 174 (2012)

26 Light management structures for reaching ultra-high efficiency Nature Mater. 11, 174 (2012)

27 Multi-junction solar cell Nature Mater. 11, 174 (2012)

28 Triple-junction tandem solar cell layer geometry Record efficiency: 43.5 % From: Richard King (Spectrolab)

29 Integrated parallel multi-junction solar cell Light management Nature Mater. 11, 174 (2012)

30 Scalable inexpensive large-area layer transfer and nanofabrication techniques Nature Mater. 11, 174 (2012)

31 Outline 4. Solving V oc < E g 1. Light coupling 2. Light trapping 3. Current collection 5. Towards 70% efficiency

32 Nature Mater. 11, 174 (2012)

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