Synergistic Redox Modulation for High‐Performance Nickel Oxide‐Based Inverted Perovskite Solar Modules

Abstract Nickel oxide (NiO x )‐based inverted perovskite solar cells stand as promising candidates for advancing perovskite photovoltaics towards commercialization, leveraging their remarkable stability, scalability, and cost‐effectiveness. However, the interfacial redox reaction between high‐valence Ni 4+ and perovskite, alongside the facile conversion of iodide in perovskite into I 2 , significantly deteriorates the performance and reproducibility of NiO x ‐based perovskite photovoltaics. Here, potassium borohydride (KBH 4 ) is introduced as a dual‐action reductant, which effectively avoids the Ni 4+ /perovskite interface reaction and mitigates the iodide‐to‐I 2 oxidation within perovskite film. This synergistic redox modulation significantly suppresses nonradiative recombination and increases the carrier lifetime. As a result, an impressive power conversion efficiency of 24.17% for NiO x ‐based perovskite solar cells is achieved, and a record efficiency of 20.2% for NiO x ‐based perovskite solar modules fabricated under ambient conditions. Notably, when evaluated using the ISOS‐L‐2 standard protocol, the module retains 94% of its initial efficiency after 2000 h of continuous illumination under maximum power point at 65 °C in ambient air.