A Diammonium‐Based Non‐Dion‐Jacobson Phase 2D Perovskite With High Durability for Efficient and Stable 2D/3D Perovskite Solar Modules

ABSTRACT Dion‐Jacobson (DJ) phase 2D perovskites have attracted much interest in photovoltaic community owing to their potential higher stability relative to 3D counterparts. The conventional wisdom has been that organic diammoniums certainly generate DJ 2D perovskites by forming bilateral hydrogen bonds with two layers of inorganic [PbI 6 ] 4− slabs. However, we herein report a diammonium‐based non‐DJ phase 2D perovskite, composed of 3 , 3′ ‐methylenediphenyldiammonium ( 3,3 ‐MDPDA 2+ ). Single‐crystal structure of the resultant 2D perovskite has a formula of ( 3,3‐ MDPDA)PbI 4 as the DJ phase, but reveals that there are two layers of 3,3 ‐MDPDA 2+ between adjacent inorganic layers and two ammonium groups of each 3,3 ‐MDPDA 2+ link to a single inorganic [PbI 6 ] 4− slab. Moreover, the 3,3 ‐MDPDA 2+ cations in the organic bilayer present unique π‐π interactions, including intralayered edge‐to‐face and interlayered parallel‐displaced configurations, respectively, leading to high stability of the diammonium‐based non‐DJ 2D perovskite. When introducing it into the 3D perovskite film to construct 2D/3D structures, resulting perovskite solar cells and modules (effective area: 50 cm 2 ) demonstrate efficiencies of 26.52% and 23.34%, respectively, with outstanding operational stability retaining 94% of initial efficiency under continuous maximum power point tracking for 1200 h.