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 I 2 , absorbs ultraviolet light, coordinates with Pb 2+ 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 cm 2 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.