Air-Processed Perovskite/Silicon Tandem Solar Cells via Iodide Oxidation Suppression

Efficient wide-bandgap (WBG) perovskite top cells are essential for high-performance perovskite/silicon tandem solar cells (TSCs), yet their fabrication in humid ambient air remains difficult because moisture- and oxygen-induced reactions deteriorate film quality and stability. Here, 4-[[4,6-bis(octylthio)-1,3,5-triazin-2-yl]amino]-2,6-bis(1,1-dimethylethyl)-phenol (BTDP) is introduced into the perovskite precursor to enable WBG perovskite formation under high-humid ambient air conditions. BTDP scavenges superoxide radical anions, inhibits I^- oxidation to I₂, absorbs ultraviolet light, coordinates with Pb²⁺ to regulate crystallization and forms a hydrophobic barrier at surfaces and grain boundaries. With this strategy, blade-coated WBG perovskite solar cells (PSCs) fabricated at 60% relative humidity deliver a power conversion efficiency (PCE) of 23.45%, which represents the highest PCE reported for air-processed WBG PSCs with bandgap ≥1.68 eV. Mini-modules with an aperture area of 14.81 cm² reach 20.12% efficiency. Moreover, the method enables ambient-air fabrication of two-terminal perovskite/tunnel oxide passivated contact (TOPCon) TSCs with a certified efficiency of 32.59%, among the highest PCEs reported for two-terminal perovskite/TOPCon TSCs. This study provides a scalable route to efficient, stable single-junction and tandem perovskite photovoltaics.