Proceedings of Online Meetup: Contemporary Stability Challenges in Hybrid Perovskite Photovoltaics (SCHP)
Publication date: 14th April 2020
Perovskite solar cells (PSCs) have demonstrated impressive performance, while their operation stability still requires substantial improvements before this technology can be successfully commercialized. There is a growing evidence that stability of PSCs is strongly dependent on the interface chemistry between the absorber films and adjacent charge transport layers, while the exact mechanistic pathways remain poorly understood.
Here we present a systematic approach for decoupling the degradation effects induced by the top electron transport layer (ETL) of the fullerene derivative PC61BM and various bottom hole-transport layer (HTL) materials assembled in p-i-n perovskite solar cells configurations. We show that chemical interaction of MAPbI3 absorber with PC61BM most aggressively affects the operation stability of solar cells. However, washing away the degraded fullerene derivative and depositing fresh ETL leads to restoration of the initial photovoltaic performance when bottom perovskite/HTL interface is not degraded. Following this approach and refreshing ETL after light soaking of the samples and before completing the solar cell architectures, we were able to compare the photostability of stacks with various HTLs. It has been shown that PEDOT:PSS and NiOx induce significant degradation of the adjacent perovskite layer under light exposure, while PTAA provides the most stable perovskite/HTL interface. ToF-SIMS analysis of fresh and aged samples allowed us to identify chemical origins of the interactions between MAPbI3 and HTLs. The proposed research methodology and the revealed degradation pathways should facilitate future development of efficient and stable perovskite solar cells.