Mapping of the dark exciton landscape in transition metal dichalcogenides

Abstract

Transition metal dichalcogenides (TMDs) exhibit a remarkable exciton physics including optically accessible (bright) as well as spin- and momentum-forbidden (dark) excitonic states. So far the dark exciton landscape has not been revealed leaving in particular the spectral position of momentum-forbidden dark states completely unclear. This has a significant impact on the technological application potential of TMDs, since the nature of the energetically lowest state determines, if the material is a direct-gap semiconductor. Here, we show how dark states can be experimentally revealed by probing the intra-excitonic 1s-2p transition. Distinguishing the optical response shortly after the excitation (< 100fs) and after the exciton thermalization (> 1ps) allows us to demonstrate the relative position of bright and dark excitons. We find both in theory and experiment a clear blue-shift in the optical response demonstrating for the first time the transition of bright exciton populations into lower lying momentum- and spin-forbidden dark excitonic states in monolayer WSe${}_2$.

References in corpus (9)

• k.p theory for two-dimensional transition metal dichalcogenide semiconductors
• Exciton band structure of monolayer MoS2
• Brightening of dark excitons in monolayers of semiconducting transition metal dichalcogenides
• Dark excitons in transition metal dichalcogenides
• Fine Structure and Lifetime of Dark Excitons in Transition Metal Dichalcogenide Monolayers
• Excitons versus electron-hole plasma in monolayer transition metal dichalcogenide semiconductors
• Exciton Relaxation Cascade in Two-dimensional Transition-metal dichalcogenides
• Dielectric Engineering of Electronic Correlations in a van der Waals Heterostructure
• Auger recombination of dark excitons in $\mathrm{W}{\mathrm{S}}_2$ and $\mathrm{WS}{\mathrm{e}}_2$ monolayers

Cited by in corpus (31)

• Exciton physics and device application of two-dimensional transition metal dichalcogenide semiconductors
• Ultrafast transition between exciton phases in van der Waals heterostructures
• Phonon-assisted Photoluminescence from Dark Excitons in Monolayers of Transition Metal Dichalcogenides
• Momentum-resolved observation of exciton formation dynamics in monolayer WS${}_2$
• Exciton propagation and halo formation in two-dimensional materials
• Hybridized intervalley moiré excitons and flat bands in twisted WSe${}_2$ bilayers
• Exciton optics, dynamics and transport in atomically thin semiconductors
• Distinctive signatures of the spin- and momentum-forbidden dark exciton states in the photo-luminescences of strained WSe${}_2$ monolayers under thermalization
• Exciton landscape in van der Waals heterostructures
• Electrical tuning of moiré excitons in MoSe${}_2$ bilayers
• Ultrafast dynamics of bright and dark excitons in monolayer WSe${}_2$ and heterobilayer WSe${}_2$/MoS${}_2$
• Dark-exciton based strain sensing in transition metal dichalcogenides
• Band nesting and exciton spectrum in monolayer MoS${}_2$
• Exploration of the bright and dark exciton landscape and fine structure of MoS${}_2$ (using G${}_0$W${}_0$-BSE)
• Analytical description of the 1s exciton linewidth temperature-dependence in transition metal dichalcogenides
• Nanosecond-scale magneto-exciton energy oscillations in quantum wells
• Microscopic modelling of exciton-polariton diffusion coefficients in atomically thin semiconductors
• Coupling of MoS${}_2$ Excitons with Lattice Phonons and Cavity Vibrational Phonons in Hybrid Nanobeam Cavities
• Probing Dark Excitons in Monolayer MoS${}_2$ by NonLinear Two-Photon Spectroscopy
• Optical fingerprint of bright and dark localized excitonic states in atomically thin 2D materials
• MoS${}_2$ flake as a van der Waals homostructure: luminescence properties and optical anisotropy
• Signatures of dark excitons in exciton-polariton optics of transition metal dichalcogenides
• Microscopic theory of the polarizability of transition metal dichalcogenides excitons: Application to WSe2
• Valley-exchange coupling probed by angle-resolved photoluminescence
• Two dimensional semiconductors: optical and electronic properties
• Third-order polarizability of interlayer excitons in hetero-bilayers
• Hybrid dark excitons in monolayer ${MoS}_2$
• Wannier Excitons Confined in Hexagonal Boron Nitride Triangular Quantum Dots
• Spectral asymmetry of phonon sideband luminescence in monolayer and bilayer WSe2
• Trion-phonon interaction in atomically thin semiconductors
• Tracking the photoinduced dynamics of a dark excitonic state in single-layer WS${}_2$ via resonant Autler-Townes splitting