Synergistic Modification of SnO₂ with H₂MoO₄ for Enhanced Performance in Perovskite Solar Cells

Perovskite solar cells (PSCs) in an n-i-p structure function well in large part due to the exceptional electrical conductivity and surface morphology of the SnO 2 -based transport layer (ETL). Here, we report a strategy to enhance the conductivity and tailor the surface morphology of the SnO 2 ETL by incorporating molybdic acid (H 2 MoO 4 ), forming a modified SnO 2:H 2 MoO 4 ETL. The incorporation of Mo 6+ ions substitutes Sn 4+ sites and inhibits the formation of oxygen vacancies (V O ), resulting in an upshifted Fermi level and enhanced electron transport efficiency of SnO 2 . The H + ions react with surface hydroxyl (−OH) defects through electrostatic interactions, suppressing surface defect generation and reducing nonradiative recombination. In addition, the in situ-formed amorphous MoO 3 in the SnO 2 matrix contributes to a denser and more uniform ETL. Consequently, the H 2 MoO 4 -modified PSCs achieve a champion PCE of 24.27%, marking a notable 9.5% boost compared to the control devices (22.17%), along with significantly enhanced long-term stability.