High Performance and Efficiency Recovery in Sn-Based Flexible Perovskite Solar Cells by Antioxidant Vanillin and Microwave Treatment

Perovskite based on Sn have attracted extensive attention to address the toxicity challenge associated with Pb-based perovskite solar cells. However, Sn-based perovskite solar cells（SPSCs）are notable for their poor stability and loss of efficiency due to rapid oxidation of Sn²⁺ to Sn⁴⁺ in air. To slow down the rapid oxidation, a number of antioxidants are suggested. Nevertheless, the antioxidant normally gets oxidized to non-antioxidizing by-products in a single-stage redox reaction and loses the function of oxidation prevention. Herein, vanillin is introduced, a natural antioxidant with a double-staged redox reaction to inhibit the oxidation of Sn²⁺ or reduce Sn⁴⁺ back to Sn²⁺, which improves the efficiency and prolongs the open-air stability of SPSCs. With 7.5% vanillin doping, an outstanding efficiency of 13.18% is achieved. Moreover, exposure of the solar cell to 160 W microwave irradiation for 3 minutes resulted in significant efficiency recovery from 88% to 96.5% at 812 hours and from 35.7% to 65.4% after 2200 hours of aging. This work reveals the potential of natural antioxidation and short microwave irradiation as suitable approaches to elevate the efficiency and lifetime of SPSCs.