Brightening of dark excitons in via tensile strain-induced excitonic valley convergence
Authors:
- Tamaghna ChowdhuryTCTamaghna Chowdhury
- Sagnik ChatterjeeSCSagnik Chatterjee
- Dibyasankar DasDDDibyasankar Das
- Ivan TimokhinITIvan Timokhin
- Pablo Díaz NúñezPNPablo Díaz Núñez
- Gokul M. A.GAGokul M. A.
- Suman ChatterjeeSCSuman Chatterjee
- Kausik MajumdarKMKausik Majumdar
- Prasenjit GhoshPGPrasenjit Ghosh
- Artem MishchenkoAMArtem Mishchenko
- Atikur RahmanARAtikur Rahman
- 12 August 2024
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 110 (8) , L081405
Abstract
Transition-metal dichalcogenides (TMDs) host tightly bound electron-hole pairs—excitons—which can be either optically bright or dark based on spin and momentum selection rules. In tungsten-based TMDs, a momentum-forbidden dark exciton is the energy ground state, and therefore, it strongly affects the emission properties. In this work, we brighten the momentum-forbidden dark exciton by placing monolayer tungsten disulfide on top of nanotextured substrates, which imparts tensile strain, modifying its electronic band structure. This enables phonon-assisted exciton scattering between momentum valleys, thereby brightening momentum-forbidden dark excitons. In addition to offering a tuning knob for light-matter interactions in two-dimensional materials, our results pave the way for designing ultrasensitive strain-sensing devices based on TMDs.Keywords
Funding Information
- European Research Council (865590)
- U.S. Department of Energy (DE-SC0012704)
- Anusandhan National Research Foundation (CRG/2021/005659)
- Simons Foundation (284558FY19)
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