Enhanced Operational Stability in Tin-Based Perovskite Solar Cells via a Natural Antioxidant

Abstract In tin-based perovskite solar cells (TPSCs), Sn(II) oxidation and illumination-induced lattice instability are primary drivers of device degradation. In this study, we introduce ellagic acid (EA), a natural antioxidant, into DMSO-free fabricated tin perovskites. Computational simulations show that EA stabilizes formamidinium sites within the perovskite lattice and effectively inhibits Sn(II) oxidation. Besides, this incorporation greatly improves film homogeneity and passivates defect traps, increasing the champion power conversion efficiency from 9.3 to 10.2%. Consequently, unencapsulated EA-incorporated devices exhibit a sixfold increase in T80 lifetime (in a nitrogen atmosphere) and a threefold increase in T60 lifetime (in dry air) at the maximum power point tracking under continuous illumination. Moreover, an EA-incorporated device achieves a 16% increment over 1000 h of day/night cycling, significantly outperforming the 7% rise of the control. These results demonstrate that natural antioxidants are a highly effective and sustainable strategy for enhancing the operational stability of lead-free TPSCs.