期刊
ACS APPLIED MATERIALS & INTERFACES
卷 14, 期 20, 页码 22973-22981出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.1c23099
关键词
halide perovskites; dynamic disorder; molecular dynamics; anharmonicity; pair distribution function; structural properties
资金
- Alexander von Humboldt-Foundation
- Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) [424709454, EXC 2089/1-390776260]
- Technical University of Munich - Institute for Advanced Study - German Excellence Initiative
- European Union [291763]
- Gauss Centre for Supercomputing e.V.
This study theoretically characterizes the vibrational interactions among atoms in the prototypical cubic CsPbBr3 and reveals the interlocking motion of neighboring Cs-Br atoms and the important local structural fluctuations on an atomic scale.
Strong deviations in the finite temperature atomic structure of halide perovskites from their average geometry can have profound impacts on optoelectronic and other device-relevant properties. Detailed mechanistic understandings of these structural fluctuations and their consequences remain, however, limited by the experimental and theoretical challenges involved in characterizing strongly anharmonic vibrational characteristics and their impact on other properties. We overcome some of these challenges by a theoretical characterization of the vibrational interactions that occur among the atoms in the prototypical cubic CsPbBr3. Our investigation based on first-principles molecular dynamics calculations finds that the motions of neighboring Cs-Br atoms interlock, which appears as the most likely Cs-Br distance being significantly shorter than what is inferred from an ideal cubic structure. This form of dynamic Cs-Br coupling coincides with very shallow dynamic potential wells for Br motions that occur across a locally and dynamically disordered energy landscape. We reveal an interesting dynamic coupling mechanism among the atoms within the nominal unit cell of cubic CsPbBr3 and quantify the important local structural fluctuations on an atomic scale.
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