Radical-Cross-Linking Molecular Anchoring Interfaces for Wide Bandgap Perovskite Solar Cells

Wide bandgap inverted perovskite solar cells (PSCs) are fundamentally constrained by interfacial nonradiative recombination and mechanical instability at the buried interface. Conventional self-assembled monolayers (SAMs), despite enabling molecular-level interface engineering, suffer from insufficient binding strength, π–π aggregation, and limited resistance to solvent and thermal stresses. Here, we report a radical-cross-linking allyl-terminated SAM that integrates extended twisting conjugation with bidentate molecular anchoring. Initiator-assisted thermal polymerization enables in situ formation of a covalently stitched interfacial network under device-compatible conditions. The cross-linked SAM enhances interfacial robustness, suppresses trap formation and halide segregation, and improves energy-level alignment for efficient charge extraction. As a result, inverted 1.68 eV PSCs achieve a power conversion efficiency of 23.71% with an open-circuit voltage of 1.268 V and markedly enhanced operational stability, while 1.54 eV devices reach 26.06% efficiency. This work establishes a radical cross-linking SAMs paradigm for constructing mechanically resilient and electronically optimized interfaces in high-performance perovskite photovoltaics.