Cross-plane coherent acoustic phonons in two-dimensional organic-inorganic hybrid perovskites

Peijun Guo, Constantinos C. Stoumpos, Lingling Mao, Sridhar Sadasivam, John B. Ketterson, Pierre Darancet, Mercouri G. Kanatzidis, Richard D. Schaller

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Two-dimensional Ruddlesden-Popper organic-inorganic hybrid layered perovskites (2D RPs) are solution-grown semiconductors with prospective applications in next-generation optoelectronics. The heat-carrying, low-energy acoustic phonons, which are important for heat management of 2D RP-based devices, have remained unexplored. Here we report on the generation and propagation of coherent longitudinal acoustic phonons along the cross-plane direction of 2D RPs, following separate characterizations of below-bandgap refractive indices. Through experiments on single crystals of systematically varied perovskite layer thickness, we demonstrate significant reduction in both group velocity and propagation length of acoustic phonons in 2D RPs as compared to the three-dimensional methylammonium lead iodide counterpart. As borne out by a minimal coarse-grained model, these vibrational properties arise from a large acoustic impedance mismatch between the alternating layers of perovskite sheets and bulky organic cations. Our results inform on thermal transport in highly impedance-mismatched crystal sub-lattices and provide insights towards design of materials that exhibit highly anisotropic thermal dissipation properties.

Original languageEnglish
Article number2019
JournalNature communications
Volume9
Issue number1
DOIs
Publication statusPublished - Dec 1 2018

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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