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Toward Long-Term Stability: Single-Crystal Alloys of Cesium-Containing Mixed Cation and Mixed Halide Perovskite

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posted on 2019-01-04, 00:00 authored by Liang Chen, Yan-Yan Tan, Zhi-Xin Chen, Tan Wang, Shu Hu, Zi-Ang Nan, Li-Qiang Xie, Yong Hui, Jing-Xin Huang, Chao Zhan, Su-Heng Wang, Jian-Zhang Zhou, Jia-Wei Yan, Bing-Wei Mao, Zhong-Qun Tian
Perovskite solar cells are strong competitors for silicon-based ones, but suffer from poor long-term stability, for which the intrinsic stability of perovskite materials is of primary concern. Herein, we prepared a series of well-defined cesium-containing mixed cation and mixed halide perovskite single-crystal alloys, which enabled systematic investigations on their structural stabilities against light, heat, water, and oxygen. Two potential phase separation processes are evidenced for the alloys as the cesium content increases to 10% and/or bromide to 15%. Eventually, a highly stable new composition, (FAPbI3)0.9(MAPbBr3)0.05­(CsPbBr3)0.05, emerges with a carrier lifetime of 16 μs. It remains stable during at least 10 000 h water–oxygen and 1000 h light stability tests, which is very promising for long-term stable devices with high efficiency. The mechanism for the enhanced stability is elucidated through detailed single-crystal structure analysis. Our work provides a single-crystal-based paradigm for stability investigation, leading to the discovery of stable new perovskite materials.