Tailoring Defects Regulation in Air-Fabricated CsPbI 3 for Efficient Inverted All-Inorganic Perovskite Solar Cells with V oc of 1.225 V.

Air fabrication of CsPbI 3 perovskite photovoltaics has been attractive and fast-moving owing to its compatibility to low-cost and up-scalable fabrication. However, due to the inevitable erosions, undesirable traps are formed in air-fabricated CsPbI 3 crystals and seriously hinder photovoltaic performance with poor reproduction. Here, 3, 5-difluorobenzoic acid hydrazide (FBJ) is incorporated as trap regulation against external erosions in air-fabricated CsPbI 3 . Theoretical simulations reveal that FBJ molecules feature stronger absorbance on CsPbI 3 than water, which can regulate trap formations for water erosions. In addition, FBJ with solid bonding interaction to CsPbI 3 can enlarge formation energy of various defects during crystallization and further suppress traps. Moreover, profiling to reductive hydrazine groups, FBJ inhibits traps for oxidation erosions. Consequently, a champion efficiency of 19.27% with an impressive V oc of 1.225 V is realized with the inverted CsPbI 3 devices. Moreover, the optimized devices present superior stability and contain 97.4% after operating at 60 °C for 600 h.