Boosting Efficiency and Stability of Planar Inverted (FAPbI 3 ) x (MAPbBr 3 ) 1− x Solar Cells via FAPbI 3 and MAPbBr 3 Crystal Powders

Solution‐processed perovskite precursors, especially for MAPbBr 3 ‐assisted FAPbI 3 crystallization, has been noted to achieve high power conversion efficiency (PCE) for perovskite solar cells (PSCs). However, this low‐temperature processed (FAPbI 3 ) x (MAPbBr 3 ) 1− x typical precursor derived from commercial products (FAI, PbI 2 , MABr, and PbBr 2 ) suffers from environmental sensitivity, poor film crystallinity and less than ideal device reproducibility. Herein, (FAPbI 3 ) x (MAPbBr 3 ) 1– x (0.80 ≤  x  ≤ 0.90)‐based planar inverted PSCs are fabricated, employing grinded monocrystalline MAPbBr 3 and powdered polycrystalline FAPbI 3 as precursors. The champion device with optimal molar ratio x  = 0.85 comprising highly crystalline larger‐grained perovskite film with enhanced carrier transport kinetics and reduced trap‐state density exhibits boosted efficiency reaching 20.50%, which shows a 22.90% improvement over typical precursors with a PCE of 16.68%. In addition, the crystal powder precursor yields obvious film stability under ambient conditions (23 °C, 65–85% humidity) for 150 days and improved device storage stability in the glove box within two months. This protocol using stock crystal powders for perovskite precursor formulation provides a relatively facile and reproducible device fabrication route for the commercialization of PSCs.