Optimizing ETL/CsPbBr3 buried interface contact for enhanced efficiency and stability of inorganic perovskite solar cells

CsPbBr₃ 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 CsPbBr₃/oxide buried interface and imperfect band alignment have impeded further efficiency enhancements. In this study, TiO₂, SnO₂, or ZnO was employed as electron transport layer (ETL) materials, respectively, in CsPbBr₃-based PSCs to optimize the band alignment at the ETL/CsPbBr₃ interface and enhance the film quality of CsPbBr₃ materials. The research findings indicate that the power conversion efficiency (PCE) of PSCs is influenced by the choice of ETL material. Specifically, TiO₂-based PSCs achieved a PCE of 10.37% efficiency, higher than SnO₂- 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/CsPbBr₃ interface. Notably, superior photovoltaic performance was consistently observed in TiO₂-based PSCs due to the substantial conduction band offset (∆E_c) at the TiO₂/CsPbBr₃ interface and the high quality of the CsPbBr₃ film. This not only enhances electron extraction at the TiO₂/CsPbBr₃ 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 TiO₂/CsPbBr₃ heterojunction exhibit high photoresponse and photodetectivity. In conclusion, this study underscores the critical importance of the buried interface contact in CsPbBr₃ and offers a direct approach for fabricating efficient and stable inorganic PSCs and PDs.

Graphical abstract