Solvent Engineering of Perovskite Crystallization for High Band Gap FAPbBr₃ Perovskite Solar Cells Prepared in Ambient Condition

High Resolution Image Download MS PowerPoint Slide High band gap FAPbBr 3 perovskite solar cells have attracted tremendous interest in recent years due to the high open circuit voltage and good stability. Commonly a two-step method is used to prepare the FAPbBr 3 perovskite film. Here a mixed solvent approach for the second step is introduced. Formamidinium bromide (FABr) in 2-propanol and methanol mixture was applied in the second step, which resulted in favorable properties such as suitable solubility, high-quality crystallization, large grain size, improved charge extraction properties, and suppressed non-radiative recombination processes, and further enhance the power conversion efficiency (PCE) from 4.06 to 7.87%. As previously reported, methylammonium chloride (MACl) can help to improve the morphology and crystallinity of perovskite. To further prove the versatility of such a mixed solvent strategy and enhance the photovoltage performance, a small amount of MACl was added to the FABr solution with mixed solvents, and a high PCE of 9.23% was achieved under ambient conditions.