Boosting Efficiency and Stability of Planar Inverted (FAPbI3)x(MAPbBr3)1−x Solar Cells via FAPbI3 and MAPbBr3 Crystal Powders

Abstract

Solution‐processed perovskite precursors, especially for MAPbBr3‐assisted FAPbI3 crystallization, has been noted to achieve high power conversion efficiency (PCE) for perovskite solar cells (PSCs). However, this low‐temperature processed (FAPbI3)x(MAPbBr3)1−x typical precursor derived from commercial products (FAI, PbI2, MABr, and PbBr2) suffers from environmental sensitivity, poor film crystallinity and less than ideal device reproducibility. Herein, (FAPbI3)x(MAPbBr3)1–x (0.80 ≤ x ≤ 0.90)‐based planar inverted PSCs are fabricated, employing grinded monocrystalline MAPbBr3 and powdered polycrystalline FAPbI3 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.