Ultrafast charge-transfer dynamics in twisted MoS${}_2$/WSe${}_2$ heterostructures

Abstract

Two-dimensional transition metal dichalcogenides (TMD) offer a unique platform for creating van-der-Waals heterojunctions with fascinating physical properties and promising applications in optoelectronics and valleytronics. Because of their typical type-II band alignment, photoexcited electrons and holes can separate via interfacial charge transfer. To understand the nature and the dynamics of this charge transfer is of utmost importance for the design and efficiency of potential devices. However, systematic studies concerning the influence of the stacking angle on the charge transfer remain sparse. Here, we apply time- and polarization resolved second-harmonic imaging microscopy to investigate the charge-transfer dynamics for three MoS${}_2$/WSe${}_2$ heterostructures with different stacking angles at a previously unattainable time-resolution of $\approx$ 6 fs. For 1.70 eV excitation energy, electron transfer from WSe${}_2$ to MoS${}_2$ is found to depend considerably on the stacking angle with the fastest transfer time observed to be as short as 12 fs. At 1.85 eV excitation energy, ultrafast hole transfer from MoS${}_2$ to hybridized states at the $\Gamma$-point or to the K-points of WSe${}_2$ has to be considered. Surprisingly, the corresponding decay dynamics show only a minor stacking-angle dependence indicating that radiative recombination of indirect $\Gamma$-K excitons becomes the dominant decay route for all samples.

References in corpus (7)

• Ultrafast Charge Transfer in Atomically Thin MoS2/WS2 Heterostructures
• Observation of Long-Lived Interlayer Excitons in Monolayer MoSe2-WSe2 Heterostructures
• Measurement of the optical dielectric function of transition metal dichalcogenide monolayers: MoS2, MoSe2, WS2 and WSe2
• Strong interlayer coupling in van der Waals heterostructures built from single-layer chalcogenides
• Evolution of Interlayer Coupling in Twisted MoS2 Bilayers
• Ultrafast transition between exciton phases in van der Waals heterostructures
• Directional Interlayer Spin-Valley Transfer in Two-Dimensional Heterostructures

Cited by in corpus (16)

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• Ultrafast dynamics of bright and dark excitons in monolayer WSe${}_2$ and heterobilayer WSe${}_2$/MoS${}_2$
• Imaging dynamic exciton interactions and coupling in transition metal dichalcogenides
• Charge transfer dynamics in MoSe${}_2$/hBN/WSe${}_2$ heterostructures
• Optical signature of cascade transitions between moiré interlayer excitons
• Probing correlations in the exciton landscape of a moiré heterostructure
• Twist angle dependent interlayer transfer of valley polarization from excitons to free charge carriers in WSe${}_2$/MoSe${}_2$ heterobilayers
• Twisted MoSe2 Homobilayer Behaving as a Heterobilayer
• Exciton-Sensitized Second-Harmonic Generation in 2D Heterostructures
• Probing excitons with time-resolved momentum microscopy
• Trion formation resolves observed peak shifts in the optical spectra of transition metal dichalcogenides
• Spatial filtering of interlayer exciton ground state in WSe2/MoS2 heterobilayer
• Charge-separated electron-hole liquid in transition metal dichalcogenide heterostructures
• Ultrafast Charge Transfer Dynamics at the MoS${}_2$/Au Interface Observed via Optical Spectroscopy under Ambient Conditions