Fast and Anomalous Exciton Diffusion in Two-Dimensional Hybrid Perovskites

Jonas D. Ziegler, Jonas Zipfel, Barbara Meisinger, Matan Menahem, Xiangzhou Zhu, Takashi Taniguchi, Kenji Watanabe, Omer Yaffe, David A. Egger, Alexey Chernikov

Research output: Contribution to journalArticlepeer-review

48 Scopus citations

Abstract

Two-dimensional hybrid perovskites are currently in the spotlight of condensed matter and nanotechnology research due to their intriguing optoelectronic and vibrational properties with emerging potential for light-harvesting and light-emitting applications. While it is known that these natural quantum wells host tightly bound excitons, the mobilities of these fundamental optical excitations at the heart of the optoelectronic applications are barely explored. Here, we directly monitor the diffusion of excitons through ultrafast emission microscopy from liquid helium to room temperature in hBN-encapsulated two-dimensional hybrid perovskites. We find very fast diffusion with characteristic hallmarks of free exciton propagation for all temperatures above 50 K. In the cryogenic regime, we observe nonlinear, anomalous behavior with an exceptionally rapid expansion of the exciton cloud followed by a very slow and even negative effective diffusion. We discuss our findings in view of efficient exciton-phonon coupling, highlighting two-dimensional hybrids as promising platforms for basic research and optoelectronic applications.

Original languageEnglish
Pages (from-to)6674-6681
Number of pages8
JournalNano Letters
Volume20
Issue number9
DOIs
StatePublished - 9 Sep 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
Copyright © 2020 American Chemical Society.

Keywords

  • 2D perovskites
  • diffusion
  • exciton-phonon interaction
  • excitons

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