Oxygen‐Rich Molecular Bridging Interface Enable High‐Performance Perovskite Solar Cells

ABSTRACT Buried interface defects and energy‐level misalignment pose major challenges in perovskite solar cells (PSCs), resulting in degradation centers for severe non‐radiative recombination that limits device performance. Here, lithium bis(oxalato)borate (LiBOB) was introduced into the electron transport layer (ETL)/perovskite interface. As a versatile Lewis base, the highly polar BOB − anions coordinate with Lewis acidic Pb 2+ and Sn 4+ . This interaction makes the perovskite precursor film uniform heterogeneous nucleation, yielding larger perovskite‐grains with minimized bulk/grain boundary defects. Simultaneously, it effectively adjusts the energy band of the SnO 2 quantum dots ETL to achieve a favorable energy‐level alignment between perovskite and SnO 2 quantum dots ETL, resulting in a reduced interfacial barrier for smooth electron transfer/extraction. Consequently, LiBOB‐based PSCs achieved a champion efficiency of 26.15%. After 3600 h under ambient conditions, these devices kept ∼91% of their initial efficiency, significantly surpassing control devices (only 53% retention).