Carbon-incorporated polysilicon interconnection layer enables robust self-assembled monolayer anchoring for perovskite/TOPCon tandem solar cells

Due to the deficiency of anchoring sites (i.e., hydroxyl groups), self-assembled monolayers (SAMs) pose a significant challenge for achieving dense and uniform coverage on textured substrates, thereby hindering the development of perovskite/silicon tandem solar cells. Here, we develop an in-situ carbon incorporation strategy for polysilicon-based tunnel recombination interconnection layers to enhance SAM adsorption and anchoring. Carbon-incorporated polysilicon exhibits a higher surface hydroxyl group density and enhanced hydrophilicity, facilitating SAM adsorption and forming robust SAM anchoring. This leads to improved uniformity and continuity of SAM coverage, along with enhanced perovskite crystallization, resulting in pinhole‑free and denser perovskite deposition on textured substrates. Moreover, the strategy further adjusts the energy level alignment of the SAM surface, facilitating hole extraction. After integration into perovskite/tunnel oxide passivating contact (TOPCon) tandems (~1 cm2), we achieve a record efficiency of 33.84% (certified at 33.50%), with excellent operation stability, retaining 80% of its initial efficiency after 800 h. Self-assembled monolayers struggle to uniformly coat textured surfaces, limiting high-efficiency perovskite and silicon tandem solar cells. Du et al. increase surface hydroxyl groups by incorporating carbon into polysilicon, enabling stable monolayer attachment and record device efficiency.