Mixed Antisolvent Strategy Enables Synergistic Crystallization Control and Defect Passivation in Perovskite Solar Cells

In the one-step solution method of perovskite film preparation, antisolvents are widely used to control perovskite crystallization, which directly influences the quality of the perovskite films. Herein, hexafluorobenzene (HFB) was involved in the mixed antisolvent (MAS) system to produce high-quality perovskite films with dual functions of crystallization control and defect passivation. Beyond improving perovskite crystallization and interface contact, a small amount of HFB remained in the perovskite and passivated uncoordinated Pb²⁺ defects. Consequently, the HFB-involved MAS-derived perovskite films exhibited higher crystallinity, smoother surfaces, better interfacial contacts, and fewer defects than those without HFB additives. These enhancements in film quality significantly improved the open-circuit voltage (V_OC) and the fill factor (FF) of the corresponding solar cells, resulting in an increase in power conversion efficiency (PCE) from 23.18% to 24.53%. Furthermore, the solar cells prepared by this method exhibited improved stability. This study highlights a facile and efficient method for simultaneously regulating perovskite crystallization and mitigating defects by incorporating functionalized mixed antisolvents, thus improving the photovoltaic performance of perovskite solar cells.