Facet Orientation and Intermediate Phase Regulation via a Green Antisolvent for High‐Performance Perovskite Solar Cells

Herein, isobutanol (IBA) as a new type of green antisolvent for improving the performance of perovskite solar cells (PSCs) is demonstrated. Compared to the commonly used chlorobenzene (CB), IBA treatment enables a preferred (111) crystal orientation, better crystallinity, enlarged grain size of the perovskite film, and penetrated grain crystal throughout the film. IBA antisolvent can effectively suppress the formation of δ‐phase and favor the formation of α‐phase during perovskite film crystallization. The superior crystal quality and preferred (111) orientation are attributed to the different interactions of DMSO with FA + induced by the introduction of IBA. As a result, a higher open circuit voltage and improved power conversion efficiency are achieved in three different compositions of PSCs compared with the conventionally used CB antisolvent, suggesting the universality of this method. The results offer instructive insight into searching for a new antisolvent in further potential applications of PSCs.