Article Ultrafast dynamics of bright and dark excitons in monolayer WSe2 and heterobilayer WSe2/MoS2

Jan Philipp Bange ; Paul Werner ; David Schmitt ; Wiebke Bennecke ; Giuseppe Meneghini ; AbdulAziz AlMutairi ; Marco Merboldt ; Kenji Watanabe SAMURAI ORCID (National Institute for Materials Science) ; Takashi Taniguchi SAMURAI ORCID (National Institute for Materials Science) ; Sabine Steil ; Daniel Steil ; R Thomas Weitz ; Stephan Hofmann ; G S Matthijs Jansen ; Samuel Brem ; Ermin Malic ; Marcel Reutzel ; Stefan Mathias

Bange_2023_2D_Mater._10_035039.pdf
Download file (1.25 MB)
Download as zip (1.03 MB)
Collection

Citation
Jan Philipp Bange, Paul Werner, David Schmitt, Wiebke Bennecke, Giuseppe Meneghini, AbdulAziz AlMutairi, Marco Merboldt, Kenji Watanabe, Takashi Taniguchi, Sabine Steil, Daniel Steil, R Thomas Weitz, Stephan Hofmann, G S Matthijs Jansen, Samuel Brem, Ermin Malic, Marcel Reutzel, Stefan Mathias. Ultrafast dynamics of bright and dark excitons in monolayer WSe2 and heterobilayer WSe2/MoS2. 2D Materials. 2023, 10 (3), 035039. https://doi.org/10.1088/2053-1583/ace067
SAMURAI

Description:

(abstract)

The energy landscape of optical excitations in mono- and few-layer transition metal dichalcogenides (TMDs) is dominated by optically bright and dark excitons. These excitons can be fully localized within a single TMD layer, or the electron- and the hole-component of the exciton can be charge-separated over multiple TMD layers. Such intra- or interlayer excitons have been characterized in detail using all-optical spectroscopies, and, more recently, photoemission spectroscopy. In addition, there are so-called hybrid excitons whose electron- and/or hole-component are delocalized over two or more TMD layers; so far, a detailed characterization of the energy landscape and dynamics of optically dark hybrid excitons is missing. In this work, using femtosecond momentum microscopy, we quantitatively compare the formation dynamics of momentum-forbidden intralayer excitons in monolayer WSe2 with the formation dynamics of momentum-forbidden hybrid excitons in heterobilayer WSe2/MoS2, and draw three key conclusions: First, we find that the energy of hybrid excitons is reduced when compared to excitons with pure intralayer character. Second, in direct comparison with microscopic modelling, we show that the momentum-forbidden intralayer and hybrid excitons are formed via exciton-phonon scattering from optically excited bright excitons. And third, we show that the efficiency for phonon absorption and emission processes in the mono- and the heterobilayer is strongly dependent on the energy alignment of the dark intralayer and hybrid excitons with respect to the optically excited bright exciton.

Rights:

Keyword: Optical excitations, hybrid excitons, charge-transfer processes

Date published: 2023-07-01

Publisher: IOP Publishing

Journal:

  • 2D Materials (ISSN: 20531583) vol. 10 issue. 3 035039

Funding:

  • saudi arabian ministry for higher education
  • Graphene Flagship 881603
  • Deutsche Forschungsgemeinschaft 217133147/SFB 1073
  • Japan Society for the Promotion of Science 20H00354
  • World Premier International Research Center MEXT
  • Engineering and Physical Sciences Research Council EP/T001038/1

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1088/2053-1583/ace067

Related item:

Other identifier(s):

Contact agent:

Updated at: 2025-02-25 16:30:36 +0900

Published on MDR: 2025-02-25 16:30:37 +0900

Filename Size
Filename Bange_2023_2D_Mater._10_035039.pdf (Thumbnail)
application/pdf 		Size 1.25 MB Detail