Integrating multifunctional interfaces via chelation-driven chemical reconstruction enables efficient and durable perovskite solar cells

Interfacial instability is a critical constraint for the practical deployment of perovskite solar cells (PSCs). It commonly arises from the metastable residual PbI₂ and deep-level defects like under-coordinated Pb²⁺. Herein, a benzeneseleninic acid (PSA)-enabled interfacial chemical reconstruction strategy, that simultaneously converts residual PbI₂, mitigates interfacial defects, and stabilizes the perovskite lattice through synergistic bidentate chelation and hydrogen bonding, is reported to significantly improve the interfacial stability. Robust Pb–O–Se chelate structures can be formed via dual-site coordination between PSA with under-coordinated Pb²⁺ and residual PbI₂. This chelation-driven interfacial reconstruction not only eliminates detrimental defects at the interface but also induces ordered molecular self-assembly, in which outward-oriented phenyl groups form a hydrophobic barrier that blocks water/oxygen intrusion, while the interfacial dipole modulates the degree of energy-level matching, thereby markedly enhancing charge extraction efficiency. Meanwhile, PSA molecules stabilize the halide sublattice through hydrogen-bond interactions, suppressing ion migration and structural degradation. Consequently, PSA-treated PSCs exhibits markedly improved efficiency (from 23.68% to 26.56%) together with substantially enhanced stability, retains 87.8% of initial efficiency after 2000 h under 60% relative humidity.