Simultaneously Mitigating Anion and Cation Defects Both in Bulk and Interface for High‐Effective Perovskite Solar Cells

Perovskite layer, as the origin of optical–electrical conversion of devices, plays a very important role in perovskite solar cells (PSCs). However, lots of lead cations and halogen anions defects inevitably exit in the bulk and surface of the perovskite layer. These defects, serve as nonradiative recombination centers, degrade the performance, and damage the stability of PSCs. Herein, a strategy that anion and cation defects on the interface and in the bulk of perovskites are simultaneously passivated by doping organic molecule 4‐aminomethyl tetrahydropyran (4‐AMPR) and the surface modification with 1‐chlorobutane (1‐CB) in/on the perovskite is demonstrated. The O atoms on 4‐AMPR can coordinate with the Pb vacancy and antisite Pb defects, as well as improve perovskite morphology. The volatilization of low‐boiling 1‐CB can passivate the halogen ion defects and promote the uniform nucleation of perovskite. The PSCs jointly optimized by 4‐AMPR and 1‐CB achieve a power conversion efficiency of 22.74% and retain 90.7% of the initial efficiency after storage in air environment (RH 10 ± 5%, 25 °C) for more than 1000 h. This research demonstrates a promising strategy for simultaneously mitigating anion and cation defects both in bulk and surface of perovskite layer and thus enhancing the performance and stability of the devices.