Distinguishing thermal fluctuations from polaron formation in halide perovskites

• DOI: 10.48550/arxiv.2502.06904
• Publication Date: 2025-02-09
• Authors: B. Zhao; Xuan‐Yan Chen; Chuan-Nan Li; Jinshan Li; Chris G. Van de W...; Xie Zhang
• Keywords: Condensed Matter - Materials Science; Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences

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