Diammonium Molecular Configuration‐Induced Regulation of Crystal Orientation and Carrier Dynamics for Highly Efficient and Stable 2D/3D Perovskite Solar Cells

Abstract The effects from the molecular configuration of diammonium spacer cations on 2D/3D perovskite properties are still unclear. Here, we investigated systematically the mechanism of molecular configuration‐induced regulation of crystallization kinetic and carrier dynamics by employing various diammonium molecules to construct Dion‐Jacobson (DJ)‐type 2D/3D perovskites to further facilitating the photovoltaic performance. The minimum average Pb‐I‐Pb angle leads to the smallest octahedral tilting of [PbX 6 ] 4− lattice in optimal diammonium molecule‐incorporated DJ‐type 2D/3D perovskite, which enables suitable binding energy and hydrogen‐bonding between spacer cations and inorganic [PbX 6 ] 4− cages, thus contributing to the formation of high‐quality perovskite film with vertical crystal orientation, mitigatory lattice distortion and efficient carrier transportation. As a consequence, a dramatically improved device efficiency of 22.68 % is achieved with excellent moisture stability.