Hybridized intervalley moiré excitons and flat bands in twisted WSe${}_2$ bilayers

Abstract

The large surface-to-volume ratio in atomically thin 2D materials allows to efficiently tune their properties through modifications of their environment. Artificial stacking of two monolayers into a bilayer leads to an overlap of layer-localized wave functions giving rise to a twist angle-dependent hybridization of excitonic states. In this joint theory-experiment study, we demonstrate the impact of interlayer hybridization on bright and momentum-dark excitons in twisted WSe${}_2$ bilayers. In particular, we show that the strong hybridization of electrons at the $\Lambda$ point leads to a drastic redshift of the momentum-dark K-$\Lambda$ exciton, accompanied by the emergence of flat moiré exciton bands at small twist angles. We directly compare theoretically predicted and experimentally measured optical spectra allowing us to identify photoluminescence signals stemming from phonon-assisted recombination of layer-hybridized dark excitons. Moreover, we predict the emergence of additional spectral features resulting from the moiré potential of the twisted bilayer lattice.

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Cited by in corpus (37)

• Moiré Excitons Correlated with Superlattice Structure in Twisted WSe${}_2$/WSe${}_2$ Homobilayers
• Tunable Phases of Moiré Excitons in van der Waals Heterostructures
• Electrical control of hybrid exciton transport in a van der Waals heterostructure
• Exciton-exciton interaction in transition metal dichalcogenide monolayers and van der Waals heterostructures
• Moiré and beyond in transition metal dichalcogenide twisted bilayers
• Twist-angle engineering of excitonic quantum interference and optical nonlinearities in stacked 2D semiconductors
• Exciton landscape in van der Waals heterostructures
• Strain-dependent exciton diffusion in transition metal dichalcogenides
• Microscopic understanding of ultrafast charge transfer in van-der-Waals heterostructures
• Electrical tuning of moiré excitons in MoSe${}_2$ bilayers
• Temporal evolution of low-temperature phonon sidebands in WSe${}_2$ monolayers
• Ultrafast dynamics of bright and dark excitons in monolayer WSe${}_2$ and heterobilayer WSe${}_2$/MoS${}_2$
• Moiré induced topology and flat bands in twisted bilayer WSe${}_2$: A first-principles study
• Stacking-dependent exciton multiplicity in WSe${}_2$ bilayers
• Chiral valley phonons and flat phonon bands in moiré materials
• Ultrafast phonon-driven charge transfer in van der Waals heterostructures
• Probing correlations in the exciton landscape of a moiré heterostructure
• Leaky exciton condensates in transition metal dichalcogenide moiré bilayers
• Excitonic Absorption Signatures of Twisted Bilayer WSe${}_2$ by Electron Energy-Loss Spectroscopy
• Electrically tunable dipolar interactions between layer-hybridized excitons
• Dynamical exciton condensates in biased electron-hole bilayers
• Excitonic theory of doping-dependent optical response in atomically thin semiconductors
• Ultrafast nano-imaging of dark excitons
• Spin-valley dynamics in alloy-based transition metal dichalcogenide heterobilayers
• Impact of atomic reconstruction on optical spectra of twisted TMD homobilayers
• Tuning exciton complexes in twisted bilayer WSe2 at intermediate misorientation
• Probing excitons with time-resolved momentum microscopy
• Spatiotemporal dynamics of moiré excitons in van der Waals heterostructures
• Direct visualization of hybrid excitons in van der Waals heterostructures
• Approaching the Intrinsic Properties of Moiré Structures Using Atomic Force Microscopy Ironing
• Excitonic thermalization bottleneck in twisted TMD heterostructures
• Interlayer exciton polaritons in homobilayers of transition metal dichalcogenides
• Electrically tunable layer-hybridized trions in doped WSe${}_2$ bilayers
• Two dimensional semiconductors: optical and electronic properties
• Atomic relaxation and flat bands in strain-engineered transition metal dichalcogenide bilayer moiré systems
• Charge quenching at defect states in transition metal dichalcogenide-graphene van der Waals heterobilayers
• Valley-controlled many-body exciton interactions in monolayer WSe${}_2$ phototransistors