Multisite Synergistic Defect Passivation via Pyridine Molecules for High‐Efficiency and Stable Perovskite Solar Cells

A critical challenge in achieving high‐efficiency and stable metal‐halide perovskite solar cells (PSCs) is trap‐mediated nonradiative charge recombination from charged defects at surfaces and grain boundaries. While molecular passivation strategies have been widely explored, developing a universal passivator capable of simultaneously addressing multiple defect types—such as undercoordinated Pb 2 + , halide vacancies I − , and organic cation disorders—remains a significant hurdle. An ideal passivator should incorporate multiple‐functional groups that can interact synergistically with diverse defects. In this work, multifunctional pyridine‐based molecules have emerged as promising candidates due to their dual role in modulating perovskite crystallization and passivating defects. Notably, 2‐mercapto‐5‐trifluoromethylpyridine (MPTM) exhibits a unique triple‐functional passivation mechanism: the thiol and pyridinic nitrogen groups coordinate with undercoordinated Pb 2 + ions, mitigating deep‐level traps; the trifluoromethyl functional group forms hydrogen bonds with FA + , suppressing its migration; and in polar solutions, MPTM undergoes isomerization to a zwitterionic thiocarbonyl imide, enabling simultaneous interactions with I − vacancies, FA + , and Pb 2 + . This synergistic defect suppression minimizes nonradiative recombination, leading to enhanced charge transport and extraction. As a result, MPTM‐passivated devices achieve a champion power conversion efficiency (PCE) of 24.32%. Furthermore, the optimized unencapsulated PSCs demonstrate outstanding environmental stability, retaining >91% of their initial PCE after 66 days in humid air.