Synergistic Dual-Interface Engineering in Perovskite Solar Cells via Chloramine Hydrochloride Molecular Bridges.

High-performance perovskite solar cells (PSCs) require synergistic passivation strategies to address defects at the electron transport layer (ETL)/perovskite interface, impacting both efficiency and long-term stability. This study introduces chloramine hydrochlorides (CAHs) - 2-Chloroethylamine Hydrochloride (CEA), Bis(2-chloroethyl)amine Hydrochloride (BCEA), and Tris(2-Chloroethyl)Amine Hydrochloride (TCEA) - as bifunctional molecular bridges to simultaneously passivate defects at both ETL (SnO) and perovskite interfaces while controlling crystallization. Density functional theory calculations showed that TCEA forms strong Sn─Cl bonds, enhancing Sn⁴ coordination. In situ characterization revealed that TCEA accelerated perovskite formation, suppressed PbI, and promoted larger grains, thus minimizing grain boundary defects. This leads to an improved electron extraction efficiency, prolonged hot-carrier cooling, and a champion power conversion efficiency (PCE) of 25.25% (compared to 23.64% for controls), with negligible hysteresis and 90% PCE retention after 1000 h under ambient conditions. This study establishes a universal molecular design strategy for dual-interface engineering in high-efficiency and stable PSCs.