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

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.