Multidentate silane bridging for stable and efficient perovskite–organic tandem solar cells

Perovskite–organic tandem solar cells (POTSCs) offer significant advantages over other perovskite-based tandem architectures owing to their straightforward processing and broad tuneability. However, the interfacial energetics disorder and resulting heterogeneous photoactive phase in wide bandgap perovskite subcells significantly undermine their long-term stability. Here, we develop a multidentate anchoring-bridging strategy that establishes a periodic passivating array that coordinates with dangling Pb²⁺ on the perovskite surface to reduce vacancy-mediated halide migration. The network with fluorinated chains reconfigures the interfacial dielectric landscape, significantly increasing the migration activation barrier for halide vacancies at the perovskite/electron transport layer interface, suppressing ion migration and significantly enchancing longevity. Poly-FPTS-treated tandem devices delivered a power conversion efficiency (PCE) of 26.5%, with a high open-circuit voltage of 2.178 V. A steady-state certified efficiency of 25.1% was achieved in Japan Electrical Safety & Environmental Technology Laboratories (JET), as reported in Solar Cell Efficiency Tables (version 65). Under continuous 1-sun illumination at the maximum power point (ISOS-L-1I protocol), these devices retained 92% of their initial efficiency after 1000 hours, and they exhibited an efficiency loss < 5% after 1056 hours of light–dark cycling (ISOS-LC-1). This work reveals the importance of treating the top perovskite/ETL contact for commercializing perovskite–organic tandem solar cells.