期刊
CHEMISTRY OF MATERIALS
卷 30, 期 16, 页码 5583-5592出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.chemmater.8b01505
关键词
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资金
- National Science Foundation (NSF) SusChem Grant [CBET-1605495, CBET-1605547]
- Department of Energy's Office of Energy Efficiency and Renewable Energy at the National Renewable Energy Laloratory
- Massachusetts Institute of Technology Energy Initiative Total Energy Fellowship
- Blue Waters Graduate Fellowship
Defect tolerance, or the resilience of electronic transport properties of a crystalline material to the presence of defects, has emerged as a critical factor in the success of hybrid lead halide perovskites as photovoltaic absorbers. A key aspect of defect tolerance is the shallow character of dominant intrinsic defects. However, while qualitative heuristics to identify other defect-tolerant materials have been proposed, in particular, the presence of a partially oxidized ns(2) cation such as Pb, no compelling comprehensive understanding of how these shallow defects arise has yet emerged. Using modern defect theory and defect calculations, we conduct a detailed investigation of the mechanisms and identify specific features related to the chemical composition and crystal structure that give rise to defect tolerance. We find that an ns(2) cation is necessary but not sufficient to guarantee shallow cation vacancies in an s-p system, and that a compound's crystal structure can ensure shallow anion vacancies in a variety of ways. Specifically, the crystal site symmetry can enforce weak interactions between the orbitals that form the defect states, thus ensuring that those defect states are shallow. We substantiate our findings by computing defect formation energies in several known as well as hypothetical materials and conclude by discussing prospects for identifying semiconductors that satisfy these criteria.
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