In n‐i‐p planar perovskite solar cells (PSCs), the electron transport layer (ETL) and the hole transporting layer play a crucial role in realizing high power conversion efficiency (PCE). Herein, a TiO2‐SDBA‐SnO2 stacked ETL is reported, where 4,4′‐sulfonyldibenzoic acid (SDBA) serves as an active passivation agent to suppress charge recombination and enhance interface quality. SDBA effectively passivates oxygen vacancies in sputtered TiO2, while simultaneously promoting SnO2 nucleation and improving film quality. Moreover, its molecular structure increases the surface free energy of the ETL, facilitating the formation of high‐quality perovskite films with larger grain sizes and fewer defects. As a result, PSCs with this optimized ETL achieve a PCE of 25.94% with excellent stability. This approach also enables the fabrication of perovskite solar modules with a certified efficiency of 22.55% over a 26.02 cm2 aperture area.