Strain engineering of transient exciton diffusion in WSe2 monolayers at cryogenic temperatures
Abstract
Tungsten-based transition metal dichalcogenides exhibit dark excitons as the energetically lowest states. These are crucial for exciton thermalization and propagation and they dominate low-temperature photoluminescence via the emergence of pronounced phonon sidebands. After a resonant excitation, highly mobile hot dark excitons are formed, which quickly thermalize into an equilibrium distribution. The application of strain modifies the exciton energy landscape and, in particular, the relative energy separation between bright and dark exciton states. The impact of strain on the transient photoluminescence and diffusion of non-equilibrium excitons has remained largely unexplored so far. In this work, we investigate the spatiotemporal exciton dynamics in strained hBN-encapsulated WSe2 monolayers at cryogenic temperatures. We demonstrate that tensile strain abruptly increases the excess energy of hot excitons, thereby accelerating their transient diffusion. We trace this back to suppressed phonon-mediated scattering from bright to dark excitons. Furthermore, we predict a periodic modulation of the transient exciton diffusion in the presence of a compressive strain resulting from strain-driven emission of M phonons. The gained microscopic insights illustrate how strain can be used to engineer transient photoluminescence and exciton diffusion in technologically promising 2D semiconductors.
Versions
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BibTeX
@misc{rosati2026strain,
title = {{Strain engineering of transient exciton diffusion in WSe2 monolayers at cryogenic temperatures}},
author = {Roberto Rosati and Mohammed Adel Aly and Robert Schmidt and Rudolf Bratschitsch and Ermin Malic},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.02513},
eprint = {2608.02513},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.02513},
}
RIS
TY - UNPB
TI - Strain engineering of transient exciton diffusion in WSe2 monolayers at cryogenic temperatures
AU - Roberto Rosati
AU - Mohammed Adel Aly
AU - Robert Schmidt
AU - Rudolf Bratschitsch
AU - Ermin Malic
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2608.02513
UR - https://arxiv.org/abs/2608.02513
AB - Tungsten-based transition metal dichalcogenides exhibit dark excitons as the energetically lowest states. These are crucial for exciton thermalization and propagation and they dominate low-temperature photoluminescence via the emergence of pronounced phonon sidebands. After a resonant excitation, highly mobile hot dark excitons are formed, which quickly thermalize into an equilibrium distribution. The application of strain modifies the exciton energy landscape and, in particular, the relative energy separation between bright and dark exciton states. The impact of strain on the transient photoluminescence and diffusion of non-equilibrium excitons has remained largely unexplored so far. In this work, we investigate the spatiotemporal exciton dynamics in strained hBN-encapsulated WSe2 monolayers at cryogenic temperatures. We demonstrate that tensile strain abruptly increases the excess energy of hot excitons, thereby accelerating their transient diffusion. We trace this back to suppressed phonon-mediated scattering from bright to dark excitons. Furthermore, we predict a periodic modulation of the transient exciton diffusion in the presence of a compressive strain resulting from strain-driven emission of M phonons. The gained microscopic insights illustrate how strain can be used to engineer transient photoluminescence and exciton diffusion in technologically promising 2D semiconductors.
ER -