Green antisolvent additive engineering to improve the performance of perovskite solar cells

High-quality perovskite films with larger grain size and fewer defects is a prerequisite for high-performance perovskite solar cells (PSCs). Antisolvent-assisted crystallization is an effective approach to obtain compact and uniform perovskite films; however, the majority of antisolvents currently applied have strong toxicity, and the control of perovskite crystallization is not easy through single antisolvent. In this work, a green antisolvent of ethyl acetate (EA) with acetylacetone (AA) additive is used to fine-tune perovskite crystallization and passivate defect, which produces uniform and compact CH3NH3PbI3 perovskite films having larger grain and fewer grain boundaries and reduced defect density. Meanwhile, the interfacial hydrophobic characteristic of the perovskite films is enhanced. At the optimized concentration of AA in EA, the power conversion efficiency (PCE) of the CH3NH3PbI3 PSCs was improved from 19.2% to 21.1% and their stability in air was also enhanced. These results present a green antisolvent additive engineering strategy to enhance the crystallinity, passivate defects, and fabricate efficient and stable PSCs.