Ultrafast Charge Carrier Relaxation in Inorganic Halide Perovskite Single Crystals Probed by Two-Dimensional Electronic Spectroscopy

Xuan Trung Nguyen, Daniel Timmer, Yevgeny Rakita, David Cahen, Alexander Steinhoff, Frank Jahnke, Christoph Lienau, Antonietta De Sio

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Halide perovskites are promising optoelectronic materials. Despite impressive device performance, especially in photovoltaics, the femtosecond dynamics of elementary optical excitations and their interactions are still debated. Here we combine ultrafast two-dimensional electronic spectroscopy (2DES) and semiconductor Bloch equations (SBEs) to probe the room-temperature dynamics of nonequilibrium excitations in CsPbBr3 crystals. Experimentally, we distinguish between excitonic and free-carrier transitions, extracting a ∼30 meV exciton binding energy, in agreement with our SBE calculations and with recent experimental studies. The 2DES dynamics indicate remarkably short, <30 fs carrier relaxation at a ∼3 meV/fs rate, much faster than previously anticipated for this material, but similar to that in direct band gap semiconductors such as GaAs. Dynamic screening of excitons by free carriers also develops on a similarly fast <30 fs time scale, emphasizing the role of carrier-carrier interactions for this material's optical properties. Our results suggest that strong electron-phonon couplings lead to ultrafast relaxation of charge carriers, which, in turn may limit halide perovskites' carrier mobilities.

Original languageEnglish
Pages (from-to)5414-5421
Number of pages8
JournalJournal of Physical Chemistry Letters
Volume10
Issue number18
DOIs
StatePublished - 19 Sep 2019
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science (all)
  • Physical and Theoretical Chemistry

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