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

High band gap FAPbBr(3) perovskite solar cellshave attractedtremendous interest in recent years due to the high open circuit voltageand good stability. Commonly a two-step method is used to preparethe FAPbBr(3) perovskite film. Here a mixed solvent approachfor the second step is introduced. Formamidinium bromide (FABr) in2-propanol and methanol mixture was applied in the second step, whichresulted in favorable properties such as suitable solubility, high-qualitycrystallization, large grain size, improved charge extraction properties,and suppressed non-radiative recombination processes, and furtherenhance the power conversion efficiency (PCE) from 4.06 to 7.87%.As previously reported, methylammonium chloride (MACl) can help toimprove the morphology and crystallinity of perovskite. To furtherprove the versatility of such a mixed solvent strategy and enhancethe photovoltage performance, a small amount of MACl was added tothe FABr solution with mixed solvents, and a high PCE of 9.23% wasachieved under ambient conditions.

Automated summary

High band gap FAPbBr(3) perovskite solar cells have attracted tremendous interest recently due to their high open circuit voltage and good stability. A mixed solvent approach for the second step of preparation was introduced, which resulted in favorable properties and improved power conversion efficiency. Addition of a small amount of MACl further enhanced the photovoltage performance, achieving a high PCE of 9.23% under ambient conditions.