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DOE OSTI · 2918040

Distinguishing Thermal Fluctuations from Polaron Formation in Halide Perovskites

Zhao, Bai-Qing [Northwestern Polytechnical University, Xi’an (China); University of California, Santa Barbara, CA (United States_] (ORCID:0009000589968943)·Qi, Jue-Yi [Northwestern Polytechnical University, Xi’an (China)] (ORCID:0009000921071207)·Xu, Xun [Northwestern Polytechnical University, Xi’an (China)] (ORCID:0000000190883107)·Chen, Xuan-Yan [Hong Kong University of Science and Technology (Guangzhou) (China)]·Li, Chuan-Nan [University of California, Santa Barbara, CA (United States)] (ORCID:0000000304030568)·Li, Jinshan [Northwestern Polytechnical University, Xi’an (China)]·Van de Walle, Chris G. [University of California, Santa Barbara, CA (United States)] (ORCID:0000000242125990)·Zhang, Xie [Northwestern Polytechnical University, Xi’an (China)] (ORCID:0000000334249253)
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Abstract

Recent angle-resolved photoelectron spectroscopy (ARPES) measurements of the hole effective mass in CsPbBr$_3$ revealed an enhancement of $\sim$50 % compared to the bare mass computed from first principles for CsPbBr$_3$ at $T = 0 K$. This large enhancement was interpreted as evidence of polaron formation. Employing accurate finite-temperature first-principles calculations, we show that the calculated hole effective mass of CsPbBr$_3$ at $T = 300 K$ can explain experimental results without invoking polarons. Thermal fluctuations are particularly strong in halide perovskites compared to conventional semiconductors such as Si and GaAs, and cannot be ignored when comparing with experiment. We not only resolve the debate on polaron formation in halide perovskites, but also demonstrate the general importance of including thermal fluctuations in first-principles calculations for strongly anharmonic materials.

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36 MATERIALS SCIENCEFOS: Physical sciencesFirst-principles calculationsMaterials Science (cond-mat.mtrl-sci)halide perovskitespolarons

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Zhao, Bai-Qing [Northwestern Polytechnical University, Xi’an (China); University of California, Santa Barbara, CA (United States_] (ORCID:0009000589968943), Qi, Jue-Yi [Northwestern Polytechnical University, Xi’an (China)] (ORCID:0009000921071207), Xu, Xun [Northwestern Polytechnical University, Xi’an (China)] (ORCID:0000000190883107), Chen, Xuan-Yan [Hong Kong University of Science and Technology (Guangzhou) (China)], Li, Chuan-Nan [University of California, Santa Barbara, CA (United States)] (ORCID:0000000304030568), Li, Jinshan [Northwestern Polytechnical University, Xi’an (China)], Van de Walle, Chris G. [University of California, Santa Barbara, CA (United States)] (ORCID:0000000242125990), Zhang, Xie [Northwestern Polytechnical University, Xi’an (China)] (ORCID:0000000334249253). 2025-06-05. Distinguishing Thermal Fluctuations from Polaron Formation in Halide Perovskites. https://doi.org/10.1103/p9h2-l2gh

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36 MATERIALS SCIENCE subjectFOS: Physical sciences subjectFirst-principles calculations subjectMaterials Science (cond-mat.mtrl-sci) subjecthalide perovskites subjectpolarons subject

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