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. Unlike other antioxidants, vanillin reduces tin perovskite material twice in a redox reaction, thereby prolonging the performance lifetime of Sn-based perovskite solar cells. The antioxidant also improves crystal quality due to its chemical interactions with perovskite, resulting in high solar cell efficiencies approximate to 13.18%. Microwave irradiation of aging solar cells results in partial efficiency recovery due to perovskite recrystallization.image