Photovoltaic Performance Improvement of All‐Inorganic CsPbBr 3 Perovskite Solar Cells by Antisolvent Assisted Crystallization

All‐inorganic CsPbBr 3 perovskite solar cells (PSCs) are expected to form semitransparent or top‐cell of tandem solar cells with Cu(In,Ga)Se 2 or crystalline silicon solar cells owing to their outstanding environmental tolerance and wide bandgap. However, the commonly solution‐processed CsPbBr 3 perovskite films usually suffer from inferior film quality. Herein, we propose antisolvent assisted crystallization method to prepare CsPbBr 3 films by multi‐step spin‐coating process. During the spin‐coating step, the underlying PbBr 2 layer is treated with anisole antisolvent in different amount of 0, 50, 100, 150, and 200 μl, respectively, and heated at 80 °C for 30 min. Thus, CsPbBr 3 films with high crystallinity, less grain boundaries and good coverage are prepared. The champion power conversion efficiency (PCE) of devices based on antisolvent treatment reaches 6.5 %, compared to that of devices without antisolvent treatment (PCE 4.97 %). Moreover, the devices treated with antisolvent without encapsulation exhibit good stability under ambient conditions. The antisolvent assisted crystallization provides an effective route for improving the quality of CsPbBr 3 films and promotes the commercialization of all‐inorganic CsPbBr 3 PSCs.