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Title: Anharmonic electron-phonon coupling in ultrasoft and locally disordered perovskites
Abstract Anharmonicity and local disorder (polymorphism) are ubiquitous in perovskite physics, inducing various phenomena observed in scattering and spectroscopy experiments. Several of these phenomena still lack interpretation from first principles since, hitherto, no approach is available to account for anharmonicity and disorder in electron–phonon couplings. Here, relying on the special displacement method, we develop a unified treatment of both and demonstrate that electron–phonon coupling is strongly influenced when we employ polymorphous perovskite networks. We uncover that polymorphism in halide perovskites leads to vibrational dynamics far from the ideal noninteracting phonon picture and drives the gradual change in their band gap around phase transition temperatures. We also clarify that combined band gap corrections arising from disorder, spin-orbit coupling, exchange–correlation functionals of high accuracy, and electron–phonon coupling are all essential. Our findings agree with experiments, suggesting that polymorphism is the key to address pending questions on perovskites’ technological applications.  more » « less
Award ID(s):
2119555 2103991
PAR ID:
10446051
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Nature Publishing Group
Date Published:
Journal Name:
npj Computational Materials
Volume:
9
Issue:
1
ISSN:
2057-3960
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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