Optimizing ETL/CsPbBr ₃ buried interface contact for enhanced efficiency and stability of inorganic perovskite solar cells

Abstract CsPbBr 3 perovskite solar cells (PSCs) have attracted significant interest for their remarkable stability under high temperatures and humidity. However, challenges such as energy loss at the CsPbBr 3 /oxide buried interface and imperfect band alignment have impeded further efficiency enhancements. In this study, TiO 2 , SnO 2 , or ZnO was employed as electron transport layer (ETL) materials, respectively, in CsPbBr 3 ‐based PSCs to optimize the band alignment at the ETL/CsPbBr 3 interface and enhance the film quality of CsPbBr 3 materials. The research findings indicate that the power conversion efficiency (PCE) of PSCs is influenced by the choice of ETL material. Specifically, TiO 2 ‐based PSCs achieved a PCE of 10.37% efficiency, higher than SnO 2 ‐ or ZnO‐based PSCs. This disparity in PCE can be attributed to variations in open‐circuit voltage, which stem from different band alignments at the ETL/CsPbBr 3 interface. Notably, superior photovoltaic performance was consistently observed in TiO 2 ‐based PSCs due to the substantial conduction band offset (∆ E c ) at the TiO 2 /CsPbBr 3 interface and the high quality of the CsPbBr 3 film. This not only enhances electron extraction at the TiO 2 /CsPbBr 3 interface but also diminishes non‐radiative recombination at the interface, as confirmed by density functional theory (DFT) calculations and experiments. Furthermore, photodetectors (PDs) based on TiO 2 /CsPbBr 3 heterojunction exhibit high photoresponse and photodetectivity. In conclusion, this study underscores the critical importance of the buried interface contact in CsPbBr 3 and offers a direct approach for fabricating efficient and stable inorganic PSCs and PDs.