Dose-Dependent Transition in Wide-Bandgap Tin-Based Perovskite Solar Cells under Low-Dose γ-Irradiation

Wide-bandgap (WBG) tin-based (Sn-) perovskites possess redox-active Sn2+/Sn4+ chemistry that fundamentally alters defect evolution under ionizing environments; however, their cumulative total ionizing dose (TID) response remains poorly understood. Here, we investigate the γ-irradiation response of WBG Sn-perovskite solar cells (PSCs) over cumulative doses from 0 to 500 Gy to elucidate cumulative TID-driven defect evolution. Low-dose exposure (≤100 Gy) reduces nonradiative recombination losses through radiation-assisted reconfiguration of pre-existing shallow defect states, increasing the average device efficiency from 6.16% to 6.79%. In contrast, higher doses (≥100 Gy) induce progressive Sn2+ oxidation, halide depletion, and deep-level trap formation, resulting in irreversible performance degradation. By delineating a transition from a low-dose defect-reconfiguration regime to a high-dose degradation regime, this work establishes an observed dose-dependent transition within the 10–100 Gy interval under the present sampling resolution and defines a redox-defect-coupled framework for understanding radiation-driven defect evolution in Sn-perovskites.