A Zwitterion Molecule Passivates the Charged Defects for High‐Performance Inverted Perovskite Solar Cells

Defects originating from the ionic nature of perovskite film are major factors that degrade the performance of perovskite solar cells (PSCs), and mitigating or removing them is essential for the implementation of high‐performance PSCs. Herein, an additive 4‐toluenesulfonic acid ammonium salt (TAAS) has been used to modify the perovskite film. The sulfonic acid groups (SO 3 − ) as an electron donor can not only regulate the growth of perovskite crystals, but also effectively passivate the positively charged defects caused by under‐coordinated Pb 2+ . The ammonium ions (NH 4 + ) can effectively passivate cation vacancies through electrostatic interactions. Furthermore, the benzene ring can trap trace I 2 generated by oxidation in the perovskite active layer and reduce the I 2 ‐induced acceptor defects. The power conversion efficiency of PSCs based on the optimized perovskite is significantly improved from 24.70% to 26.02%, and the stability of PSCs is also advanced.