CIGS und Perowskit Solarzellenforschung an der Empa

Transcription

1 CIGS und Perowskit Solarzellenforschung an der Empa Dr. Stephan Buecheler Contact: Direct: Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for, Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland; 15. Nationale Photovoltaik Tagung März 2017

2 Alkali addition after growth (alkali fluoride and Se co-evaporation, T sub ~350 C) D. Rudmann et al., Appl. Phys. Lett. 84, 1129, A. Chirilă & P. Reinhard et al., Nature Materials 12, 1107, P. Reinhard et al., Chem. Mater., DOI: /acs.chemmater.5b02335,

3 Cu(In,Ga)Se 2 thin film solar cells Flexible CIGS solar cell: 20.4% efficiency Flexible CIGS mini-module: 16.9% efficiency 8 monolithically interconnected cells V OC = 711 mv per cell Laser scribing by Flisom company 3

4 CIGS solar cells and mini-modules / state-of-the-art : NaF PDT 2: reduced optical losses 3: GGI grading and Na doping 4

5 This list is not exhaustive Effect of alkaline post deposition treatement (PDT) Surface nano-structuring Changes in PL decay Changes in apparent doping Surface is Cu and Ga depleted ~3.5 µm Enhanced diffusion of Cd Exchange of alkaline elements F. Pianezzi et al., Journal of Applied Physics, 114, 2013 P. Reinhard et al., Nano Let 15, 3334 (2015). A. Chirilă & P. Reinhard et al., Nature Materials 12, 1107, (2013). F. Pianezzi et al., Phys. Chem. Chem. Phys., 16,

6 Efficiency potential of Cu(In,Ga)Se 2 thin film solar cells Jsc [ma/cm 2 ] Voc [mv] FF [%] Eff [%] Empa cell on PI SQ-limit (1.15 ev) Losses compared to SQ-limit -17% -17% -9.3% Envisaged improvement for CIGS (maybe not all applicable on flexible substrate): Jsc by ~10% Voc by ~9% FF by ~3% (38.5 ma/cm 2 ) (800 mv) (81%) efficiency of 25% for CIGS solar cells is a realistic goal Development supported by HZ2020 project Sharc25 with 11 European partners 6

7 Polycrystalline thin film solar cells with efficiency >30%? Price breakdown of residential PV system Thermodynamic losses in PV Other costs Engineering procurement & construction Tandem can help here Balance of systems Inverter PV module Module efficiency is critical to reduce non-module costs Source: PV Status Report 2014, A. Jager-Waldau, JRC Reports A. Polman, H.A. Atwater, Nature Materials 11, (2012) Chalcogenide and Perovskite thin film solar cells are promising for tandem devices: Tunable, low bandgap Polycrystalline, thin film absorbers on various substrates deposited in costeffective manner 7

8 Tandem configurations 4-terminal tandem + Both cells can operate in resp. MPP + simple stacking possible - Additional optical losses in transparent contacts - Two DC circuits 2-terminal (monolithic) tandem + Less optical losses in transparent contacts + Only one DC circuit - Current matching required for all incident angles - Reduced energy yield due to different temperature and spectral dependence 8

9 Theoretical efficiency limit for 2 junction tandem solar cells 2-terminal tandem 4-terminal tandem 29.8% 41.4% E G of state-of-the-art CIGS 42.2% 43.6% E G of state-of-the-art CIGS 38.0% 43.6% CIS - E G 43.8% 44.5% CIS - E G Perovskite adjusted E G Perovskite adjusted E G Calculated maximum efficiency in the detailed balance limit for AM1.5G incident light. No optical losses included! W. Schockley and H. J. Queisser, Detailed balanced limit of efficiency of p-n junction solar cells, J. Appl. Phys. 32, 510 (1961). 9

10 Perovskite solar cells in substrate configuration F. Fu et al., Nat. Energy. 2, (2016) 10

11 NIR-transparent perovskite solar cells in substrate configuration > 80% F. Fu et al., Nat. Energy. 2, (2016) Average NIR-transmittance >80% between nm 11

12 Photovoltaic performance Negligible J-V hysteresis Steady state efficiency of 16.1% w/o ARC F. Fu et al., Nat. Energy. 2, (2016) 12

13 Low temperature coefficient Perovskite: -0.22%/ C CIGS: -0.32%/ C CdTe:-0.28%/ C c-si:-0.44%/ C Important metric for field applications K. Bush et al., Adv. Mater. 28, (2016) F. Fu et al., Nat. Energy. 2, (2016) 13

14 All-thin-film Perovskite-CI(G)S tandem solar cells 22.1% h = 6.0% h = 19.2% h = 16.1% 20.9% h = 4.8% h = 13.0% h = 16.1% F. Fu et al., Nat. Energy. 2, (2016) 14

15 Summary and Outlook Alkaline treatment yielded efficiency leap in CIGS solar cells Perovskite and CIGS devices are suitable partners for high efficiency tandem devices Clear efficiency gain in tandem devices compared to sub cells already achieved all-thin-film PV device in 4t tandem configuration with efficiency above 22% sub-cell efficiency band gap of top and bottom cell transmission through top cell recombination layer NIR response in bottom cell stability of top cell 15

16 Acknowledgements Thanks for your attention EU-commission FP7 project «hipocigs» (project number: ) EU-commission FP7 project «R2R-CIGS» (project number: ) EU-commission Horizon 2020 project «Sharc25» (project number:641004) Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number REF The Competence Center for Energy and Mobility in ETH Domain (DURSOL, CONNECT-PV) The Swiss National Science Foundation / The Swiss Federal Office of Energy / NanoTera / Comission for Tech. and Innovation The Laboratory for Nanoscale Materials Science at Empa (SIMS, XPS) The Laboratory for Electronics/Metrology/Reliability at Empa (SEM) The Laboratory for Analytical Chemistry at Empa (ICP-MS) Flisom AG All current and former members of the Lab for Thin Films and Photovoltaics at Empa Contact Laboratory for Thin Films and Photovoltaics Empa - Swiss Federal Laboratories for Überlandstrasse 129, 8600 Dübendorf, Switzerland stephan.buecheler@empa.ch Disclaimer: The opinions expressed and arguments employed herein do not necessarily reflect the official views of the Swiss Government or the European Agency 16