Dual-Site Competitive Coordination Eliminates Residual DMSO for Thermally and Moisture-Stable Perovskite Solar Cells

The commercialization of perovskite solar cells (PSCs) is critically impeded by instability under thermal and humid conditions, primarily originating from residual dimethyl sulfoxide (DMSO) trapped in crystalline intermediates during solution processing. Here, we introduce eperisone hydrochloride (EH) as a dual-site passivator that eliminates DMSO residues through competitive coordination. The carbonyl group of EH binds to Pb2+, displacing it from PbI2–DMSO complexes and generating mesoporous PbI2 frameworks that facilitate solvent volatilization. Concurrently, the tertiary amine directs formamidinium cation (FA+) alignment via hydrogen bonding, while chloride ions fill iodide vacancies to suppress ion migration. After crystallization, EH migrates to grain boundaries to form a low-hydrophilic barrier that blocks moisture. These synergies enable planar PSCs to achieve 26.06% efficiency and outstanding stability, retaining 90.39% of their initial efficiency after 1200 h (ISOS-L-3, 85 °C, MPP tracking) and 90.12% after 600 h (ISOS-D-3, 85 °C/85% RH).