Revealing superoxide-induced degradation in lead-free tin perovskite solar cells. Issue 12 (9th November 2022)

• Record Type: Journal Article
• Authors: Zhang, Zhihao; Tian, Xuesong; Wang, Can; Jin, Jialun; Jiang, Yiting; Zhou, Qin; Zhu, Jingwei; Xu, Jianbin; He, Rui; Huang, Yuanfang; Ren, Shengqiang; Chen, Cong; Gao, Peng; Long, Run; Zhao, Dewei
• Is Part Of: Energy & environmental science. Volume 15:Issue 12(2022)
• Page Start: 5274
• Page End: 5283
• Publication Date: 2022-11-09
• Subjects: Energy conversion -- Periodicals; Fuel switching -- Periodicals; Environmental sciences -- Periodicals; Environmental chemistry -- Periodicals; 333.79
• DOI: 10.1039/d2ee02796h
• Languages: English
• ISSNs: 1754-5692

Abstract

Abstract : Sn-based perovskite FASnI3 suffers more severe degradation under light/O2 than only O2 exposure, which is caused by the large amount of superoxide formation at numerous iodine vacancies through the reaction between O2 and photoexcited electrons. Abstract : The poor stability of lead (Pb)-free tin (Sn)-based perovskites under only oxygen (O2 ) exposure has attracted extensive research, while their stability under simultaneous light and O2 (light/O2 ) exposure is unexplored. Herein, we found that the (NH2 )2 CHSnI3 (FASnI3 ) perovskite degrades more severely when exposed to light/O2 than only O2, which we attribute to the superoxide generated via the reaction between O2 and photoexcited electrons. We propose the superoxide-induced degradation routes of FASnI3 . Fluorescent molecular probe results indicate higher yield of superoxide in FASnI3 than in FAPbI3 . Density functional theory simulation results rationalize that the formation energy of the most preferred sites (iodine vacancy, VI ) for superoxide formation in FASnI3 is much lower than that in FAPbI3 ; meanwhile, superoxide formation at VI is more energetically favorable in FASnI3 . A targeted strategy by incorporating halide-containing additives is applied to fill the VI in FASnI3 to suppress superoxide formation. Combined with superoxide yield measurement, capacitance-dominated characterization can systematically differentiate the reduction of surface and interior VI after modification. Understanding the degradation mechanism of FASnI3 upon light/O2 exposure manifests the fatal effect of superoxide on the stability of Sn-based perovskite solar cells.