Halogen-Functional Molecules for Synergistic Multi-Defect Healing in High-Performance Perovskite Solar Cells

Defect complexity and dynamic coupling in perovskites limit single-target passivation and often incur lattice damage when highly reactive agents are used. Here, we introduce two additives, perfluoropinacol (PFP) and 2,6-dichlorobenzyl chloride (DCB), to achieve synergistic, multiple defect passivation while promoting controlled crystallization. With multiple functional sites targeting distinct defect species (such as V_I vacancy, V_Pb vacancy, Pb_I antisite, and so on), PFP and DCB act synergistically to achieve comprehensive, integrated defect passivation. The combined action improves defect passivation, delivering high-performance devices: champion PCEs of 25.47% (n-i-p) and 26.47% (p-i-n). Unencapsulated devices exhibit durable stability, retaining 95% of initial efficiency after 1300 h at 65°C and 94% after 1000 h under 1-sun maximum power point tracking (MPPT). This cooperative strategy provides a practical pathway to simultaneously regulate crystallization and suppress deep/shallow defects, advancing efficient and stable perovskite photovoltaics toward industrial deployment.