Traps and transport resistance are the next frontiers for stable non-fullerene acceptor solar cells
- Technische Universität Chemnitz (Germany)
- Friedrich-Alexander-Universität Erlangen-Nürnberg (Germany); Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (HI ERN) (Germany)
- Friedrich-Alexander-Universität Erlangen-Nürnberg (Germany); South China Normal University (SCNU), Guangzhou (China)
- Univ. of Bayreuth (Germany)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
- Univ. of Bern (Switzerland)
- Technische Universität Dresden (Germany)
- Friedrich-Alexander-Universität Erlangen-Nürnberg (Germany); Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (HI ERN) (Germany); South China Univ. of Technology (SCUT), Guangzhou (China)
- Durham Univ. (United Kingdom)
Stability is one of the most important challenges facing material research for organic solar cells (OSC) on their path to further commercialization. In the high-performance material system PM6:Y6 studied here, we investigate degradation mechanisms of inverted photovoltaic devices. We have identified two distinct degradation pathways: one requires the presence of both illumination and oxygen and features a short-circuit current reduction, the other one is induced thermally and marked by severe losses of open-circuit voltage and fill factor. We focus our investigation on the thermally accelerated degradation. Our findings show that bulk material properties and interfaces remain remarkably stable, however, aging-induced defect state formation in the active layer remains the primary cause of thermal degradation. The increased trap density leads to higher non-radiative recombination, which limits the open-circuit voltage and lowers the charge carrier mobility in the photoactive layer. Furthermore, we find the trap-induced transport resistance to be the major reason for the drop in fill factor. Our results suggest that device lifetimes could be significantly increased by marginally suppressing trap formation, leading to a bright future for OSC.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division; German Research Foundation (DFG)
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1905510
- Journal Information:
- Nature Communications, Vol. 13, Issue 1; ISSN 2041-1723
- Publisher:
- Nature Publishing GroupCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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