Temporal Evolution of Low-Temperature Phonon Sidebands in Transition Metal Dichalcogenides
Research output: Contribution to journal › Research article › Contributed › peer-review
Contributors
Abstract
Low-temperature photoluminescence (PL) of hBN-encapsulated monolayer tungsten diselenide (WSe2) shows a multitude of sharp emission peaks below the bright exciton. Some of them have been recently identified as phonon sidebands of momentum-dark states. However, the exciton dynamics behind the emergence of these sidebands has not been revealed yet. In this joint theory-experiment study, we theoretically predict and experimentally observe time-resolved PL, providing microscopic insights into the thermalization of hot excitons formed after optical excitation. In very good agreement between theory and experiment, we demonstrate a spectral red-shift of phonon sidebands on a time scale of tens of picoseconds, reflecting the phonon-driven thermalization of hot excitons in momentum-dark states. Furthermore, we predict the emergence of a transient phonon sideband that vanishes in the stationary PL. The obtained microscopic insights are applicable to a broad class of 2D materials with multiple exciton valleys.
Details
Original language | English |
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Pages (from-to) | 2756-2764 |
Number of pages | 9 |
Journal | ACS photonics |
Volume | 7 |
Issue number | 10 |
Publication status | Published - 21 Oct 2020 |
Peer-reviewed | Yes |
Externally published | Yes |
Keywords
ASJC Scopus subject areas
Keywords
- dark excitons, formation of phonon sidebands, transition metal dichalcogenides