Improved Performance and Stability of Perovskite Solar Modules by Regulating Interfacial Ion Diffusion with Nonionic Cross‐Linked 1D Lead‐Iodide

Abstract Long‐term stability has become the major obstacle for the successful large‐scale application of perovskites devices. Owing to the ionic nature of metal‐halide perovskites, the interfacial ion diffusion can induce irreversible degradation under operational conditions, which presents a great challenge to realize stable perovskite solar modules. Here, a diphenylphosphine oxide compound, ethane‐1,2‐diylbis(diphenylphosphine oxide) (DPPO) is introduced to coordinate with lead iodide and form a cross‐linked 1D Pb₃I₆‐DPPO (1D‐PbI₂) complex. These judiciously designed cross‐linked nonionic low‐dimensional lead halide/organic adducts can passivate the defects of perovskite while acting as a robust ion diffusion barrier, thus significantly improving the electronic quality and intrinsic stability of perovskite films. As a result, high‐performance inverted (p‐i‐n) solar modules with a champion efficiency approaching 19% (a certified stabilized efficiency of 17.8%) for active device areas above 17 cm² without the use of antisolvents, accompanied by outstanding operational stability under heat stress and continuous illumination are achieved.