Polar Fluctuations in Metal Halide Perovskites Uncovered by Acoustic Phonon Anomalies

Peijun Guo, Yi Xia, Jue Gong, Konstantinos Stoumpos, Kyle M. McCall, Grant C.B. Alexander, Zhiyuan Ma, Hua Zhou, David J. Gosztola, John B Ketterson, Mercouri Kanatzidis, Tao Xu, Maria K.Y. Chan, Richard Daniel Schaller*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Solution-processable metal halide perovskites (MHPs) offer great promise for efficient light-harvesting and -emitting devices because of their long carrier lifetime and superior carrier transport properties. Similar to traditional oxide perovskites, MHPs exhibit strong dynamic disorders that may further impact their electronic properties. Here we investigate the coherent acoustic phonons of inorganic and organic-inorganic (hybrid) MHP single crystals (CsPbCl3, MAPbCl3, CsPbBr3, MAPbBr3, FAPbBr3, MAPbI3, and FAPbI3) using pump-probe reflection spectroscopy. We show significant phonon softening in the cubic phase of all compositions close to the cubic-to-tetragonal phase transition temperature. Such phonon softening in conjunction with strong acoustic damping is attributed to pretransitional polar fluctuations. Comparison of MHPs with different compositions show that the degree of pretransitional fluctuations is correlated with the size rather than the dipole moment of the A-site cations, and further with the size of the anions.

Original languageEnglish (US)
Pages (from-to)2463-2469
Number of pages7
JournalACS Energy Letters
Issue number10
StatePublished - Oct 13 2017

ASJC Scopus subject areas

  • Chemistry (miscellaneous)
  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Materials Chemistry


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