Interfacial Engineering by Metallic Ions and Organic Ammonium Ligand Passivation for Perovskite Solar Cells

Surface passivation is essential for minimizing ion vacancies and trap centers in perovskite crystals, but the mechanisms governing enhanced interfacial charge separation and suppressed recombination remain an active area of research. In this study, a synergistic post-treatment approach employing phenethylammonium iodide (PEAI) and antimony iodide (SbI₃) is introduced, which not only passivates the traps but also facilitates the charge transportation at the interface. By using advanced characterization techniques, we confirm the dual incorporation of PEAI and Sb⁰, revealing improved charge carrier dynamics and surface passivation. The p-type metallic Sb doping, suitable band energy alignment, reduced defect density, and minimized surface ion vacancies collectively enhance the interfacial charge separation, thus resulting in an enhanced power conversion efficiency (PCE). Notably, unencapsulated devices with PEAI+Sb treatment demonstrated impressive thermal stability, retaining over 80% of the initial PCE after 5 h of continuous heating at 85°C temperature under N₂ condition. This theoretical findings confirm that Sb preferentially binds to the PEA phenyl ring, yielding a stable interfacial configuration, stabilizing the surface and enhancing the interfacial charge transport. This work presents an effective strategy and provides insights into charge modulation using metallic ions, contributing to improved device efficiency and stability in perovskite solar cells.