Chemically Cross‐Linking SnO 2 Nanoparticles and Promoting Charge Transport by π – π Interaction of Conjugated Molecules for Efficient and Stable Air‐Processed Regular Perovskite Solar Cells

ABSTRACT SnO 2 nanoparticles (NPs) based electron transport layer (ETL) usually suffers from poor stability and insufficient charge transport capability resulting from defects, agglomeration, and inefficient electron transfer between SnO 2 NPs, hindering the further development of n‐i‐p regular perovskite solar cells (PSCs). Here, we report hydroxyl‐group‐functionalized pyrene conjugated molecules, namely 1,3,6,8‐Tetra (4‐hydroxyphenyl) pyrene (THPP), to improve the durability and electron transport ability of SnO 2 ‐based ETL through the synergy of multisite chemical bonding and π – π interaction of conjugated THPP. Meanwhile, THPP modulation results in defect reduction, residual stress release, and perovskite crystallization improvement at the buried interface. The resultant regular PSCs achieve a promising power conversion efficiency (PCE) of 25.69%, among the highest PCEs reported for air‐processed PSCs. Furthermore, the THPP‐modulated devices demonstrate exceptional operational stability, maintaining 90.8% of their original PCEs after continuous maximum power point tracking for 1000 h. This work highlights the importance of functional group‐functionalized conjugated molecules in promoting charge transport and transfer between SnO 2 NPs within ETL, representing an important step forward toward the practical employment of regular PSCs.