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 SnO2-based transport layer (ETL). Here, we report a strategy to enhance the conductivity and tailor the surface morphology of the SnO2 ETL by incorporating molybdic acid (H2MoO4), forming a modified SnO2:H2MoO4 ETL. The incorporation of Mo6+ ions substitutes Sn4+ sites and inhibits the formation of oxygen vacancies (VO), resulting in an upshifted Fermi level and enhanced electron transport efficiency of SnO2. 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 MoO3 in the SnO2 matrix contributes to a denser and more uniform ETL. Consequently, the H2MoO4-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.