Molecular Integration Strategy Enables Simultaneous Modulation of Crystal Growth and Interfacial Energy Loss for Efficient Inverted Perovskite Solar Cells

Abstract Severe interfacial energy loss and inferior crystal quality remain key limitations for high‐performance perovskite solar cells (PSCs). Herein, we report a multifunctional molecule, 1,3‐propanediamine dimercaptoacetate (PDA(AcSH) 2 ), designed through a molecular‐integration strategy to address these challenges simultaneously. The PDA 2+ cations preferentially accumulate at the perovskite/C 60 interface, establishing a field‐effect passivation that suppresses interfacial contact induced non‐radiative recombination. Meanwhile, the AcSH – anions are homogeneously distributed throughout the perovskite layer, mediating crystal growth and passivating charged traps via dual binding of ─SH and ─COO – groups. The reducible ─SH groups in AcSH – also convert photo‐thermally generated I 2 /I 3 – species into I – , forming reversible S─S dimers that photodecompose under UV light illumination to regenerate ─SH groups. This enables a self‐sustaining redox cycle for dynamic defect healing and enhances both precursor and film stability. Consequently, the optimized small‐area (0.09‐cm 2 ) device achieves impressive efficiency of 26.88% and a non‐radiative voltage loss of only 64 mV. The strategy is readily scalable, delivering efficiencies of 24.92% and 22.73% for 1‐cm 2 device and 12.96‐cm 2 mini‐module, respectively. This work highlights the effectiveness of rational molecular design in mitigating both bulk and interfacial energy losses, paving the way for the next generation of high‐performance, stable, and scalable PSCs.