Solvent Engineering of Perovskite Crystallization for High Band Gap FAPbBr<sub>3</sub> Perovskite Solar Cells Prepared in Ambient Condition
Yawen Liu, Bin Cai, Hao Yang, Gerrit Boschloo, Erik M. J. Johansson
Abstract
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.