Thermal Cross-Linking Hole-Transport Self-Assembled Monolayers for Perovskite Solar Cells

Inverted perovskite solar cells (PSCs) adopting hole-transport self-assembled monolayers (SAMs) face the challenge of inadequate interfacial affinity and inherent instability. A thermal cross-linking SAM design strategy is herein reported to simultaneously improve their surface wettability and thermal stability. The in situ cross-linking networks of molecular-engineered SAMs promote charge transport at the perovskite buried interface. A champion efficiency of 24.17% was achieved for 1.56 eV bandgap PSCs, outperforming non-cross-linked counterparts (22.02%). Over 90% initial efficiency was retained after 1000 h of exposure at 100 °C. Cross-linked SAMs also endow 1.25 eV PSCs with an impressive efficiency of 22.05%. This research offers valuable insights for designing inherently stable SAMs to promote the development of inverted PSCs.