Beyond Self‐Assembled Molecules: Hydrogen‐Bonding‐Regulated Crystallization of Wide‐Bandgap Perovskite for High‐Performance Perovskite‐Silicon Tandem Photovoltaics

ABSTRACT Wide‐bandgap (WBG) perovskites crystallization is essential for high‐efficiency perovskite–silicon tandem solar cells (TSCs), yet their fabrication on self‐assembled molecules (SAMs) is often challenged by solvent‐induced damage and uncontrolled packing. Here, we report an interfacial engineering strategy that goes beyond conventional SAM modification by introducing a thiophen‐3‐ylmethanamine hydrochloride (3‐TMA) molecular layer between the SAM and perovskite photo‐active layer. The aromatic thiophene units establish strong π ‑ π stacking interactions with the underlying SAM, forming a solvent‐resistant interlayer that stabilizes the anchored SAM structure during solution processing. Meanwhile, hydrogen‐bonding interactions between 3‐TMA and the perovskite precursors effectively decelerate crystallization, promoting uniform nucleation and high‐quality WBG perovskite films. The resulting interface exhibits improved energy‐level alignment and reduced interfacial stress, facilitating efficient charge transport and enhanced device stability. Consequently, single‐junction WBG perovskite devices with bandgaps of 1.67 and 1.84 eV achieve champion power conversion efficiencies (PCEs) of 23.17% and 19.61%, respectively. When integrated into monolithic perovskite‒silicon TSCs, the strategy enables PCEs of 33.21% (certified 32.13%) for rigid tandems and 31.03% (certified 30.34%) for flexible tandems. Encapsulated devices retain 92.3% of their initial performance after 1000 h of continuous 1 sun illumination at room temperature.