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.

Pb-related imperfections (surface or halide vacancy induced uncoordinated Pb2+, Pb-I antisite, and Pb2+ 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 Pb2+ 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.