Surface lattice engineering through three-dimensional lead iodide perovskitoid for high-performance perovskite solar cells

Surface modification of organic-inorganic halide perovskite thin films represents a promising approach to enhance the efficiency and stability of perovskite solar cells. Here, we synthesized N-methyl-1,3-propane diammonium diiodide (Me-PDAI2) and found that Me-PDA2+ can template a three-dimensional “perovskitoid” structure (Me-PDA)Pb2I6. Simple surface treatment with Me-PDAI2 on top of a standard (FAPbI3)0.85(MAPbI2Br)0.10(CsPbI3)0.05 perovskite induces the formation of a thin (Me-PDA)Pb2I6 perovskitoid surface layer, leading to smoother surface texture, longer charge-carrier lifetime, higher charge-carrier mobility, and a reduced surface-defect density. With the perovskitoid surface modification, the device efficiency is significantly improved from 20.3% to 22.0% along with enhanced stability in both shelf life (ISOS-D-1 stability) and operation (ISOS-L-1 stability). We further demonstrated that the perovskitoid surface engineering approach is applicable to various perovskite compositions, including CsFAMA-, FAMA-, and MA-based lead halide perovskites, making perovskitoid an important design motif for perovskite surface engineering for enhanced device performance and stability.