Ultraviolet‐Assisted Perovskite Crystallization for High‐Performance Solar Cells

Highly crystalized perovskite film with smooth surface is of great importance to obtain high photovoltaic performances. Herein, UV irradiation is applied to the perovskite films during their thermal annealing process. It is revealed that UV irradiation treatment can largely improve perovskite crystallization and reduce defects. This greatly improves power conversion efficiency (PCE) and environmental stability of the resulted solar cells (ITO/SnO 2 /perovskite/Spiro‐OMeTAD/Au). By combining CH 3 O‐PEAI surface passivation, an outstanding PCE of 23.24% is achieved.