Dark excitons in transition metal dichalcogenides

Abstract

Monolayer transition metal dichalcogenides (TMDs) exhibit a remarkably strong Coulomb interaction that manifests in tightly bound excitons. Due to the complex electronic band structure exhibiting several spin-split valleys in the conduction and valence band, dark excitonic states can be formed. They are inaccessibly by light due to the required spin-flip and/or momentum transfer. The relative position of these dark states with respect to the optically accessible bright excitons has a crucial impact on the emission efficiency of these materials and thus on their technological potential. Based on the solution of the Wannier equation, we present the excitonic landscape of the most studied TMD materials including the spectral position of momentum- and spin-forbidden excitonic states. We show that the knowledge of the electronic dispersion does not allow to conclude about the nature of the material's band gap, since excitonic effects can give rise to significant changes. Furthermore, we reveal that an exponentially reduced photoluminescence yield does not necessarily reflect a transition from a direct to a non-direct gap material, but can be ascribed in most cases to a change of the relative spectral distance between bright and dark excitonic states.

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Cited by in corpus (96)

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• Phonon-assisted Photoluminescence from Dark Excitons in Monolayers of Transition Metal Dichalcogenides
• Exciton diffusion in monolayer semiconductors with suppressed disorder
• Exciton Relaxation Cascade in Two-dimensional Transition-metal dichalcogenides
• The role of momentum-dark excitons in the elementary optical response of bilayer WSe${}_2$
• Cavity control of Excitons in two dimensional Materials
• Momentum-resolved observation of exciton formation dynamics in monolayer WS${}_2$
• Giant Valley-Zeeman Splitting from Spin-Singlet and Spin-Triplet Interlayer Excitons in WSe2/MoSe2 Heterostructure
• Exciton-exciton interaction in transition metal dichalcogenide monolayers and van der Waals heterostructures
• Exciton propagation and halo formation in two-dimensional materials
• Multipath optical recombination of intervalley dark excitons and trions in monolayer WSe${}_2$
• Impact of strain on the excitonic linewidth in transition metal dichalcogenides
• Theory of exciton dynamics in time-resolved ARPES: intra- and intervalley scattering in two-dimensional semiconductors
• Exciton optics, dynamics and transport in atomically thin semiconductors
• Strain control of hybridization between dark and localized excitons in a 2D semiconductor
• Nonclassical Exciton Diffusion in Monolayer WSe2
• Mapping of the dark exciton landscape in transition metal dichalcogenides
• Excitonic structure of the optical conductivity in MoS${}_2$ monolayers
• Boosting quantum yields in 2D semiconductors via proximal metal plates
• 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
• Unveiling valley lifetimes of free charge carriers in monolayer WSe${}_2$
• Spinorial formulation of the GW-BSE equations and spin properties of excitons in 2D Transition Metal Dichalcogenides
• Exciton-Phonon Coupling and Band-Gap Renormalization in Monolayer WSe${}_2$
• Strain-dependent exciton diffusion in transition metal dichalcogenides
• Excitonic emission in van-der-Waals nanotubes of transition metal dichalcogenides
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• Indirect bandgap of hBN-encapsulated monolayer MoS2
• Brightening of spin- and momentum-dark excitons in transition metal dichalcogenides
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• Electrical tuning of moiré excitons in MoSe${}_2$ bilayers
• Spin States Protected from Intrinsic Electron-Phonon-Coupling Reaching 100 ns Lifetime at Room Temperature in MoSe${}_2$
• Dark-exciton driven energy funneling into dielectric inhomogeneities in two-dimensional semiconductors
• Ultrafast dynamics of bright and dark excitons in monolayer WSe${}_2$ and heterobilayer WSe${}_2$/MoS${}_2$
• Temporal evolution of low-temperature phonon sidebands in WSe${}_2$ monolayers
• Quenching of Intervalley Exchange Coupling in the Presence of Momentum-Dark States in TMDCs
• High efficiency dark-to-bright exciton conversion in carbon nanotubes
• Interaction-driven transport of dark excitons in 2D semiconductors with phonon-mediated optical readout
• Dark-exciton based strain sensing in transition metal dichalcogenides
• Tracking Dark Excitons with Exciton Polaritons in Semiconductor Microcavities
• Band nesting and exciton spectrum in monolayer MoS${}_2$
• Excitons and carriers in transient absorption and time-resolved ARPES spectroscopy: an abinitio approach
• Probing correlations in the exciton landscape of a moiré heterostructure
• Exciton-phonon-scattering: A competition between bosonic and fermionic nature of bound electron-hole pairs
• Exploration of the bright and dark exciton landscape and fine structure of MoS${}_2$ (using G${}_0$W${}_0$-BSE)
• Delocalization of dark and bright excitons in flat-band materials and the optical properties of V${}_2$O${}_5$
• Impact of dark excitons on Förster type resonant energy transfer between dye molecules and atomically thin semiconductors
• Analytical description of the 1s exciton linewidth temperature-dependence in transition metal dichalcogenides
• Visualization of dark excitons in semiconductor monolayers for high-sensitivity strain sensing
• Microscopic modelling of exciton-polariton diffusion coefficients in atomically thin semiconductors
• Nanosecond-scale magneto-exciton energy oscillations in quantum wells
• Direct Observation of Intravalley Phonon Scattering of 2s Excitons in MoSe${}_2$ and WSe${}_2$ Monolayers
• Moiré Engineering of Spin-Orbit Coupling in Twisted Platinum Diselenide
• Magnetoexcitons in transition-metal dichalcogenides monolayers, bilayers, and van der Waals heterostructures
• Phonon signatures in spectra of exciton polaritons in transition metal dichalcogenides
• Charge Density Wave Activated Excitons in TiSe${}_2$-MoSe${}_2$ Heterostructures
• Emergence of 6-particle "hexciton'' states in WS${}_2$ and MoSe${}_2$ monolayers
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• Light-matter coupling and non-equilibrium dynamics of exchange-split trions in monolayer WS2
• Spin-valley dynamics in alloy-based transition metal dichalcogenide heterobilayers
• Ultrafast nano-imaging of dark excitons
• Effects of parallel electric and magnetic fields on Rydberg excitons in buckled two-dimensional materials
• Circumventing the polariton bottleneck via dark excitons in 2D semiconductors
• Optical fingerprint of bright and dark localized excitonic states in atomically thin 2D materials
• Probing excitons with time-resolved momentum microscopy
• Monolayer Semiconductor Auger Detector
• Signatures of dark excitons in exciton-polariton optics of transition metal dichalcogenides
• Tensile strain induced brightening of momentum forbidden dark exciton in WS${}_2$
• Intrinsic edge excitons in two-dimensional MoS${}_2$
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• Spectral asymmetry of phonon sideband luminescence in monolayer and bilayer WSe2
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• Fast Interlayer Energy Transfer from the Lower Bandgap MoS2 to the Higher Bandgap WS2
• Engineering strong coupling in ultra-compact photonic crystal/2D material platforms
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• Tracking the photoinduced dynamics of a dark excitonic state in single-layer WS${}_2$ via resonant Autler-Townes splitting
• Radiative Decay of Dark Exciton Related Emission in a Sandwiched Monolayer WSe2 Revealed by Room Temperature Micro and Nano Photoluminescence