Managing Pb‐Related Imperfections via Rationally Designed Aniline Derivative with Bilateral Cyano and Acetyl Groups as Lewis Base for High‐Efficiency Perovskite Solar Cells Exceeding 24%

Abstract Pb‐related imperfections (surface or halide vacancy induced uncoordinated Pb 2+ , Pb‐I antisite, and Pb 2+ vacancy defects) of the ionic crystal perovskite film seriously restrict the photovoltaic performance of perovskite solar cells (PSCs). Here, an aniline derivative N‐(4‐cyanophenyl)acetamide (CAL) is rationally designed, incorporating bilateral functional sites of cyano and acetyl groups, acting as Lewis base molecule for managing the Pb‐related imperfections in perovskite surface through post‐treatment. Theoretical calculation and experimental verification together proved the reduced defect density, improved crystallinity, and inhibited ion migration in the CAL‐modified perovskite. Precisely, cyano as a side group and acetyl as another side group can both coordinate with Pb 2+ for its low electrostatic potential energy. Further, the aniline core and the π‐π conjugate structure in the benzene ring of the ligand tend to form a dimer to improve the mobility for carrier transportation and collection. The strategy demonstrates a champion PCE of 24.35% for the air‐processed PSCs with over 1200 hours of maximum power point tracking (MPPT) stability. This study presents a comprehensive approach to overcoming the current Pb‐related imperfections induced limitations in PSCs, paving the way for their integration into mainstream solar technologies.