Healing the Buried Interface by a Plant-Derived Green Passivator for Carbon-Based CsPbIBr<sub>2</sub> Perovskite Solar Cells
Ziting Qi, Jiabao Li, Xinyu Zhang, Jie Dou, Qiyao Guo, Yuanyuan Zhao, Peizhi Yang, Qunwei Tang, Jialong Duan
Abstract
Perovskite solar cells (PSCs) have attracted extensive attention in photovoltaic applications owing to their superior efficiency, and the buried interface plays a significant role in determining the efficiency and stability of PSCs. Herein, a plant-derived small molecule, ergothioneine (ET), is adopted to heal the defective buried interface of CsPbIBr 2 -based PSC to improve power conversion efficiency (PCE). Because of the strong interaction between Lewis base groups (–C═O and –C═S) in ET and uncoordinated Pb 2+ in the perovskite film from the theoretical simulations and experimental results, the defect density of the CsPbIBr 2 perovskite film is significantly reduced, and therefore, the nonradiative recombination in the corresponding device is simultaneously suppressed. Consequently, the target device achieves a high PCE of 11.13% with an open-circuit voltage ( V OC ) of 1.325 V for hole-free, carbon-based CsPbIBr 2 PSCs and 14.56% with a V OC of 1.308 V for CsPbI 2 Br PSCs. Furthermore, because of the increased ion migration energy, the detrimental phase segregation in this mixed-halide perovskite is weakened, delivering excellent long-term stability for the unencapsulated device in ambient conditions over 70 days with a 96% retention rate of initial efficiency.