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Structural Dynamics Descriptors for Metal Halide Perovskites.

Published version

Published version
Peer-reviewed

Repository DOI


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Authors

Liang, Xia 
Klarbring, Johan 
Baldwin, William J 

Abstract

Metal halide perovskites have shown extraordinary performance in solar energy conversion technologies. They have been classified as "soft semiconductors" due to their flexible corner-sharing octahedral networks and polymorphous nature. Understanding the local and average structures continues to be challenging for both modeling and experiments. Here, we report the quantitative analysis of structural dynamics in time and space from molecular dynamics simulations of perovskite crystals. The compact descriptors provided cover a wide variety of structural properties, including octahedral tilting and distortion, local lattice parameters, molecular orientations, as well as their spatial correlation. To validate our methods, we have trained a machine learning force field (MLFF) for methylammonium lead bromide (CH3NH3PbBr3) using an on-the-fly training approach with Gaussian process regression. The known stable phases are reproduced, and we find an additional symmetry-breaking effect in the cubic and tetragonal phases close to the phase-transition temperature. To test the implementation for large trajectories, we also apply it to 69,120 atom simulations for CsPbI3 based on an MLFF developed using the atomic cluster expansion formalism. The structural dynamics descriptors and Python toolkit are general to perovskites and readily transferable to more complex compositions.

Description

Keywords

3403 Macromolecular and Materials Chemistry, 34 Chemical Sciences, 3406 Physical Chemistry

Journal Title

J Phys Chem C Nanomater Interfaces

Conference Name

Journal ISSN

1932-7447
1932-7455

Volume Title

127

Publisher

American Chemical Society (ACS)
Sponsorship
Engineering and Physical Sciences Research Council (EP/X035859/1)