Sulfur‐Substituted SAMs Induce Pb─S Antibonding Hybridization for Efficient and Durable Perovskite‐Silicon Tandems

ABSTRACT Further improvements in tandem efficiency and long‐term operational stability critically depend on regulating the buried perovskite interface, where interfacial disorder and residual strain often dominate nonradiative losses and degradation pathways. In contrast to conventional carbazole‐based SAMs used in p–i–n architectures, the sulfur‐substituted SAM developed in this work is designed to directly interact with the perovskite lattice, enabling modulation of the local hybridization at the buried interface. Here we demonstrate that a sulfur‐substituted carbazole‐based SAM forms Pb─S antibonding hybrid states at the buried perovskite interface, reconstructing the interfacial energetic structure and yielding a chemically reinforced hole‐selective contact. Density functional theory and spectroscopic analyses confirm the formation of Pb─S antibonding interactions with optimized interfacial energetics. This interfacial chemical reinforcement suppresses nonradiative recombination, relaxes residual lattice strain, and enables rapid hole extraction under operating conditions. Integrated into monolithic perovskite–silicon tandems, this strategy delivers certified power conversion efficiencies exceeding 33% together with markedly enhanced operational stability under maximum power point tracking.