Phonon-Mediated and Weakly Size-Dependent Electron and Hole Cooling in CsPbBr3 Nanocrystals Revealed by Atomistic Simulations and Ultrafast Spectroscopy

Simon C. Boehme*, Stephanie Ten Brinck, Jorick Maes, Nuri Yazdani, Felipe Zapata, Kai Chen, Vanessa Wood, Justin M. Hodgkiss, Zeger Hens, Pieter Geiregat, Ivan Infante

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

We combine state-of-the-art ultrafast photoluminescence and absorption spectroscopy and nonadiabatic molecular dynamics simulations to investigate charge-carrier cooling in CsPbBr3 nanocrystals over a very broad size regime, from 0.8 to 12 nm. Contrary to the prevailing notion that polaron formation slows down charge-carrier cooling in lead-halide perovskites, no suppression of carrier cooling is observed in CsPbBr3 nanocrystals except for a slow cooling (over ∼10 ps) of "warm" electrons in the vicinity (within ∼0.1 eV) of the conduction band edge. At higher excess energies, electrons and holes cool with similar rates, on the order of 1 eV ps-1 carrier-1, increasing weakly with size. Our ab initio simulations suggest that cooling proceeds via fast phonon-mediated intraband transitions driven by strong and size-dependent electron-phonon coupling. The presented experimental and computational methods yield the spectrum of involved phonons and may guide the development of devices utilizing hot charge carriers.

Original languageEnglish
Pages (from-to)1819-1829
Number of pages11
JournalNano Letters
Volume20
Issue number3
Early online date12 Feb 2020
DOIs
Publication statusPublished - 11 Mar 2020

Keywords

  • Charge-carrier cooling
  • electron-phonon coupling
  • excited-states dynamics
  • hot carriers
  • lead-halide perovskite nanocrystal
  • nonadiabatic molecular dynamics

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