The Spacer Cation with Disulfide Bond for Efficient and Stable Low‐Dimensional Dion–Jacobson Perovskite Solar Cells

Low‐dimensional (LD) perovskite has provided an exciting avenue for exploring stable perovskite solar cells (PSCs). However, PSCs based on LD perovskites still suffer from poor efficiency owing to unfavorable charge carrier dynamics. Here, cystamine (CYS) is employed as a ligand to construct LD Dion‐Jacobson (LDDJ) perovskite (CYS)MAn‐1PbnI3n+1 (n = 1, 2, 3…, MA: methylamine) for improving carrier properties. The disulfide bond not only changes the polarization characteristic but also increases the coupling between inorganic slabs due to the low barrier of rotation around the S‐S axis, thus reducing the exciton binding energy of CYS‐based LDDJ perovskite. Disulfide bonds provide a scene for charge localization in the interlayer region, which is conducive to reducing the anisotropy of charge transfer. Thanks to these merits, the (CYS)MA4Pb5I16 film delivers improved carrier diffusion length (electron for 1345 nm and hole for 950 nm) and mobility (9.23 cm2 V−1 S−1). As a result, the (CYS)(MA)4Pb5I16 PSC achieves a champion power conversion efficiency (PCE) of 16.52%, which is much higher than that of HDA and BA cations‐based PSCs (HDA: 1,6‐Hexanediamine, BA: Butylamine). Furthermore, the state‐of‐the‐art device only lost 8% of its initial PCE after 1600 h in the atmosphere. A novel ligand cystamine (CYS) is introduced to construct low‐dimensional Dion‐Jacobson perovskite, which achieves excellent charge transport and low exciton binding energy. The (CYS)(MA)4Pb5I16 film shows diminished defect densities and heightened light responsivity, leading to the CYS‐based perovskite solar cells achieving a champion efficiency of 16.52% with significant stability.