中国物理学会期刊网
Chin. Phys. Lett.  2018, Vol.35 Issue (3): 036104  DOI:10.1088/0256-307X/35/3/036104
Intrinsic Instability of the Hybrid Halide Perovskite Semiconductor CH$_{3}$NH$_{3}$PbI$_{3}$$^*$
1Key Laboratory for Computational Physical Sciences (MOE), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 2004332Key Laboratory of Polar Materials and Devices (MOE), East China Normal University, Shanghai 2002413Center for Sustainable Chemical Technologies and Department of Chemistry, University of Bath, Bath BA2 7AY, UK4Beijing Computational Science Research Center, Beijing 100094>

Abstract

The organic-inorganic hybrid perovskite CH$_{3}$NH$_{3}$PbI$_{3}$ has attracted significant interest for its high performance in converting solar light into electrical power with an efficiency exceeding 20%. Unfortunately, chemical stability is one major challenge in the development of CH$_{3}$NH$_{3}$PbI$_{3}$ solar cells. It was commonly assumed that moisture or oxygen in the environment causes the poor stability of hybrid halide perovskites, however, here we show from the first-principles calculations that the room-temperature tetragonal phase of CH$_{3}$NH$_{3}$PbI$_{3}$ is thermodynamically unstable with respect to the phase separation into CH$_{3}$NH$_{3}$I + PbI$_{2}$, i.e., the disproportionation is exothermic, independent of the humidity or oxygen in the atmosphere. When the structure is distorted to the low-temperature orthorhombic phase, the energetic cost of separation increases, but remains small. Contributions from vibrational and configurational entropy at room temperature have been considered, but the instability of CH$_{3}$NH$_{3}$PbI$_{3}$ is unchanged. When I is replaced by Br or Cl, Pb by Sn, or the organic cation CH$_{3}$NH$_{3}$ by inorganic Cs, the perovskites become more stable and do not phase-separate spontaneously. Our study highlights that the poor chemical stability is intrinsic to CH$_{3}$NH$_{3}$PbI$_{3}$ and suggests that element-substitution may solve the chemical stability problem in hybrid halide perovskite solar cells.
收稿日期:2018-02-09

基金资助

The work at Fudan University was supported by the Special Funds for Major State Basic Research, National Natural Science Foundation of China (NSFC), and Project of Shanghai Municipality (16520721600). S.C. was supported by NSFC under Grant No 91233121, Shanghai Rising-Star Program (14QA1401500) and CC of ECNU. The work at Bath was supported by the Royal Society, the ERC and EPSRC under Grant Nos EP/M009580/1 and EP/K016288/1. S.H.W. was supported by the National Key Research and Development Program of China under Grant No 2016YFB0700700, and the National Natural Science Foundation of China under Grant Nos 51672023, 11634003 and U1530401.

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[英文]
Yue-Yu Zhang, Shiyou Chen, Peng Xu, Hongjun Xiang, Xin-Gao Gong, Aron Walsh, Su-Huai Wei. Intrinsic Instability of the Hybrid Halide Perovskite Semiconductor CH$_{3}$NH$_{3}$PbI$_{3}$$^*$[J]. CPL, 2018, 35(3): 036104.
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