Radiation‐Hardened Perovskite Solar Cells Enabled by Redox‐Active V ₂ O <i> _x </i> Hole Transport Layer for Space Applications

Recent advances in space missions have motivated increased research into photovoltaic technologies with improved tolerance to radiation environments in space. Here, we evaluate proton radiation resilience in perovskite solar cells via an employment of a vanadium (V) oxide (V 2 O x )/self‐assembled layer (SAM) bilayer hole transport layers (HTLs). We show that the V 2 O x /SAM bi‐HTL initially promotes more efficient charge extraction, as evidenced by enhanced photoluminescence quenching, while higher proton irradiation doses progressively weaken this benefit, consistent with the irradiation‐driven interfacial modification rather than significant absorber degradation. Notably, X‐ray photoelectron spectroscopy reveals irradiation‐induced reduction of V 2 O x , with oxygen vacancy formation and increased V 4+ content, indicating a redox‐active interface that promotes hole extraction while buffering proton‐induced interfacial degradation. In addition, analysis of the Pb core level reveals that SAM‐only devices exhibit the emergence and growth of metallic Pb species after proton irradiation, whereas devices incorporating V 2 O x act as a redox buffer that suppress metallic Pb formation across proton irradiations. This work first demonstrates the effects of metal oxide charge transport layer engineering on radiation‐hardened perovskite interfaces and advances the development of durable, lightweight photovoltaic technologies for space power applications.