Dual Vapor‐Phase Treatment Driven Subsurface Reorganization for 3D Passivation Networks toward Ultralow Interfacial Energy Loss in Perovskite Photovoltaics

Band misalignment and defect‐mediated non‐radiative recombination persist as critical bottlenecks in wide‐bandgap perovskite solar cells (PSCs). Herein, a dual vapor‐phase treatment (DVPT) synergizing dipole self‐assembly with solvent‐induced secondary Ostwald ripening, is developed to address interfacial energy losses. Theoretical and experimental analysis reveal that gas‐phase interactions between ligands and perovskite enhance the binding strength and energy level modulation. Yet the sole application of gas‐phase passivation is demonstrated to intensify interfacial inhomogeneity and subsurface energy barriers. To mitigate this challenge, polar solvent fumigation enables spatially selective reconstruction of defective crystallites to induce planar‐depth dipolar homogenization for establishing steady‐state 3D passivation frameworks. This integrated process fundamentally reconstructs interfacial energy distribution and reorganizes subsurface crystallization, which reduces exciton binding energy and accelerates charge transfer while minimizing the quasi‐Fermi level splitting losses. Consequently, inverted 1.77 eV wide‐bandgap PSCs achieve a fill factor of 84.43% and a champion efficiency of 20.36%, surpassing state‐of‐the‐art counterparts. By bridging molecular design, interfacial thermodynamics, and crystallization kinetics, this work paves the way for high‐performance, scalable perovskite tandem photovoltaics.