High Efficiency Tin Halide Perovskite Solar Cells with Over 1 Micrometer Carrier Diffusion Length

Abstract Sn²⁺ oxidation and halide migration are recognized as the major constraints for high‐performance tin halide perovskite solar cells (TPSCs), as they increase the defect state density and thus decrease the carrier lifetime and diffusion length. In this study, two chloride salts of thiophene derivatives are reported to interact with Sn²⁺ through ligand bonding and immobilize halide ions through hydrogen bonding. Due to the stronger interactions between 1‐(2‐thiophene)ethylamine hydrochloride (α‐TEACl) and the perovskite components, better defect passivation is realized. In addition, thanks to the coordination ability, the lattice stability of tin perovskite is enhanced, and the photoluminescence carrier lifetime and carrier diffusion length are substantially extended from 4.51 ns and 180.78 nm to 23.17 ns, and 1102.20 nm, respectively, which are both among the highest reported values for tin halide perovskites. Consequently, the target device with α‐TEACl achieved a power conversion efficiency (PCE) of up to 14.02%. At the same time, the α‐TEACl device showed excellent long‐term operational stability, retaining ≈92% of the initial efficiency after 2000 h aging in the N₂ atmosphere. This work provides a new perspective for regulating the defect passivation and ion migration in lead‐free tin halide perovskites.