Radiation-Hardened Perovskite Solar Cells Enabled by Redox-Active V₂O _x 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 (V₂O _x )/self-assembled layer (SAM) bilayer hole transport layers (HTLs). We show that the V₂O _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 V₂O _x , with oxygen vacancy formation and increased V⁴⁺ 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 V₂O _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.