Dual Interfacial Engineering Enables Efficient and Reproducible CsPbI2Br All-Inorganic Perovskite Solar Cells.

CsPbI2Br all-inorganic perovskite has shown superior photovoltaic properties particularly excellent phase and thermal stability, while the complicated film growth process requires additional research. Herein, the nucleation and crystallization process of the CsPbI2Br perovskite film is assisted by methyl acetate anti-solvent treatment. Additionally, a tailored SnO2 nanoparticle/TiO2 nanocrystal structured double electron transport layers (ETLs) is designed to remove the interfacial energy barrier, thus enhancing charge transfer and decrease charge recombination at the CsPbI2Br/ETL interfaces. Through synergistically dual interfacial engineering, we have demonstrated the preparation of a compact CsPbI2Br polycrystalline film with ordered and homogeneous grain size as well as ideal interfacial energy level alignment. In consequence, stable CsPbI2Br all-inorganic perovskite solar cells with the best power conversion efficiency of 15.86% has been successfully achieved together with a high open-circuit voltage of 1.23 V and a fill factor of 82.29%. We believe that the results here demonstrate efficient approaches to achieve high-quality inorganic perovskites for promoting their optoelectronic applications.