Simultaneous Chemical Crosslinking of SnO2 and Perovskite for High‐Performance Planar Perovskite Solar Cells with Minimized Lead Leakage

SnO 2 ‐based planar perovskite solar cells (PSCs) have attracted extensive attention owing to their simple structure and low‐temperature processing. However, the imperfect interface contact caused by surface defects and energy‐level mismatches greatly hinder the further improvement of the efficiency and stability of PSC. Herein, a multifunctional interfacial crosslinking agent D‐penicillamine (DPM) is introduced to improve the interface contact between SnO 2 and upper perovskite. Through systematical analysis, it is found that the DPM used to modify SnO 2 can simultaneously passivate the defects on the surface of SnO 2 via esterification reaction, promote the charge extraction in perovskite by adjusting the interface energy‐level arrangement, and improve the quality of perovskite film by forming coordination bond with lead ions. These merits eventually assist DPM‐modified PSCs and achieve an impressive efficiency of 24.09%, whereas the controlled device only shows an efficiency of 22.44%. In addition, an unencapsulated DPM‐modified PSC exhibits better storage stability, thermal stability, and light stability than the controlled device, as well as in situ absorption capacity of leaked lead ions.