Comparative study on radiation resistance of tin–lead and pure lead perovskite solar cells

Abstract

Perovskite solar cells (PSCs) offer promising opportunities for reducing the cost of space power. However, their radiation tolerance in the harsh space environment remains a critical requirement. In this work, we demonstrate that tin–lead (Sn–Pb) mixed perovskite, which enables the fabrication of all-perovskite tandem solar cells, exhibits significantly enhanced radiation resistance compared to conventional lead-only perovskites. A total ionizing dose (TID) test reveals that the power conversion efficiency (PCE) of CH₃NH₃Pb_0.7Sn_0.3I₃ PSCs decreases by 31% after exposure to 0.75 kGy and by 67% after 10 kGy γ-ray irradiation. In contrast, CH₃NH₃PbI₃ based devices suffer from much greater degradation, with PCE reductions of 48% and 90%, respectively. Considering the origins of such difference in radiation-induced PCE gradation, we find that the CH₃NH₃Pb_0.7Sn_0.3I₃ film retains its crystalline structure even after 10 kGy radiation, whereas CH₃NH₃PbI₃ is completely degraded. Based on Monte-Carlo simulations, we find that the formation of the critical radiation-induced defects, iodine vacancies and interstitial iodine, which are known as the primary defects to disrupt the perovskite lattice, is significantly suppressed in Sn–Pb mixed perovskites. Furthermore, we find that while interstitial iodines act as deep-level defects in CH₃NH₃PbI₃, they behave as shallow-level defects in CH₃NH₃Pb_0.7Sn_0.3I₃. This difference further reduces the impact of radiation-induced defects on carrier lifetime and mobility in Sn–Pb mixed perovskites. These findings suggest that Sn–Pb mixed perovskites hold great potential for space photovoltaic applications due to their superior stability under severe space radiation environments.