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Strain-Activated Exciton-Phonon Coupling in MoS2 Monolayers

In molybdenum-based monolayer dichalcogenides, phonon-assisted light emission from momentum-dark excitons is suppressed because the mediating phonon modes are forbidden by crystal symmetry. Students learn how biaxial strain lowers the point-group symmetry to activate previously forbidden hole-phonon (A') scattering channels, and how first-principles Bethe-Salpeter calculations of exciton-phonon matrix elements quantify the resulting enhancement of phonon-assisted photoluminescence.

Dr. Theopolis Text

Strain-Induced Activation of Symmetry-Forbidden Exciton-Phonon Couplings for Enhanced

Phonon-assisted photoluminescence in molybdenum-based monolayer transition-metal dichalcogenides is normally weak because the momentum-dark intervalley excitons that would emit couple only weakly to …