Molecular Disaggregation‐Bridging Engineered SnO 2 Interfaces for Scalable Perovskite Photovoltaics

ABSTRACT Scalable perovskite photovoltaics are limited by the coupled challenges of unstable SnO 2 colloids and defect‐rich buried interfaces, which together undermine film uniformity and charge extraction. While existing strategies typically target either colloidal stabilization or interface passivation alone, their single‐function nature restricts effectiveness for large‐area processing. Here, we introduce potassium dihydrogen phosphate (KH 2 PO 4 ) as a dual‐functional modifier that produces a molecular disaggregation–bridging effect (MDBE). Dihydrogen phosphate anions regulate the colloidal organization of commercial SnO 2 dispersions, contributing to smoother and more uniform electron‐transport layers, while simultaneously establishing phosphate‐mediated interfacial coordination at the buried SnO 2 /perovskite interface. This integrated regulation suppresses trap‐assisted recombination and promotes uniform perovskite crystallization. Consequently, perovskite devices fabricated via blade coating in combination with vacuum evaporation reach a PCE of 25.34%, and 5 × 5 cm 2 modules (12 cm 2 active area) deliver 23.16% with only 8% loss upon scaling. MDBE thereby provides a unified and cost‐effective interface‐engineering strategy that overcomes the limitations of conventional single‐function additives, enabling reliable and high‐performance large‐area perovskite photovoltaics.