Probing the Disorder Inside the Cubic Unit Cell of Halide Perovskites from First-Principles

Xiangzhou Zhu, Sebastián Caicedo-Dávila, Christian Gehrmann, David A. Egger

Research output: Contribution to journalReview articlepeer-review

15 Scopus citations

Abstract

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 CsPbBr3and quantify the important local structural fluctuations on an atomic scale.

Original languageEnglish
Pages (from-to)22973-22981
Number of pages9
JournalACS Applied Materials and Interfaces
Volume14
Issue number20
DOIs
StatePublished - 25 May 2022

Keywords

  • anharmonicity
  • dynamic disorder
  • halide perovskites
  • molecular dynamics
  • pair distribution function
  • structural properties

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