Electron‐Deficient Defects Repair and Residual PbI ₂ Management toward Air‐Processed High‐Performance Perovskite Solar Cells

Abstract Addressing abundant undercoordinated Sn 4+ /Pb 2+ defects and residual PbI 2 in perovskite solar cells (PSCs) is the crux to implement high‐performance regular (n‐i‐p) PSCs in ambient air and driving commercialization. Herein, a chemical bridging agent between SnO 2 and perovskite, namely 1‐ethyl‐3‐methylimidazole mesysulfonate (EMIMS), is introduced. The oxygen‐rich functional group in EMIMS not only reduces the surface hydroxide (─OH) defects on the SnO 2 layer, but also chelates the undercoordinated Pb 2+ on the perovskite film. The reduction of these electron‐deficient defects minimizes the loss of nonradiative combination of carriers and accelerates electron extraction/transfer at the buried interface. Notably, the all‐air prepared n‐i‐p PSCs modified by EMIMS achieve a high efficiency of 25.20%, and the unencapsulated device retains initial efficiency of above 90% after 2000 h in high temperature or humid environment. This study supplies a valid strategy for the application of oxygen‐rich functional groups in the preparation of high‐quality PSCs in ambient air.