Managing Interface Defects via Mixed-Salt Passivation toward Efficient and Stable Perovskite Solar Cells

Iodine vacancies and uncoordinated Pb⁰ defects existing at the perovskite surface have been widely demonstrated to induce deep-level defects, which can greatly limit improvement of the efficiency and stability of perovskite solar cells (PSCs). In this work, a novel strategy is proposed for functionalizing perovskite surface by using trimethylsulfoxonium iodide (TMSI), which can enhance the defect formation energy and inhibit Pb⁰ defects. Meanwhile, TMSI modification also can fill the iodine vacancies of perovskite surface-terminating ends. Consequently, the optimized device shows the improved charge dynamics and the reduced energy losses, achieving a champion efficiency of up to 24.03% along with excellent air-storage and thermal stabilities. This work offers guidelines for more efficient and stable PSCs based on the management of interface defects.