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Title: Effects of size mismatch of halide ions on the phase stability of mixed halide perovskites
Abstract

The phase stability of mixed halide perovskites plays a vital role in the performance and reliability of perovskite-based devices and systems. In this work, we incorporate the contribution of the strain energy due to the size mismatch of halideions in Gibbs free energy for the analysis of the phase stability of mixed halide perovskites. Analytical expressions of the chemical potentials of halide ions in mixed halide perovskites are derived and used to determine the critical atomic fractions of halide ions for the presence of spinodal decomposition (phase instability). The numerical analysis of CH3NH3PbIxBr3-xmixed halide perovskite reveals the important role of the mismatch strain from halide ions in controlling the phase instability of mixed halide perovskite, i.e., increasing the mismatch strain widens the range ofxfor the phase separation of mixed halide perovskites. To mitigate the phase instability associated with the strain energy from intrinsic size mismatch and/or light-induced expansion, strain and/or field engineering, such as high pressure, can be likely applied to introduce strain and/or field gradient to counterbalance the strain gradient by the mismatch strain and/or light-induced expansion.

 
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Award ID(s):
2018411
PAR ID:
10497607
Author(s) / Creator(s):
Publisher / Repository:
IOPscience
Date Published:
Journal Name:
Physica Scripta
Volume:
99
Issue:
2
ISSN:
0031-8949
Page Range / eLocation ID:
025937
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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