Ultrafast Charge Transfer in Atomically Thin MoS2/WS2 Heterostructures

Abstract

Van der Waals heterostructures have recently emerged as a new class of materials, where quantum coupling between stacked atomically thin two-dimensional (2D) layers, including graphene, hexagonal-boron nitride, and transition metal dichalcogenides (MX2), give rise to fascinating new phenomena. MX2 heterostructures are particularly exciting for novel optoelectronic and photovoltaic applications, because 2D MX2 monolayers can have an optical bandgap in the near-infrared to visible spectral range and exhibit extremely strong light-matter interactions. Theory predicts that many stacked MX2 heterostructures form type-II semiconductor heterojunctions that facilitate efficient electron-hole separation for light detection and harvesting. Here we report the first experimental observation of ultrafast charge transfer in photo-excited MoS2/WS2 heterostructures using both photoluminescence mapping and femtosecond (fs) pump-probe spectroscopy. We show that hole transfer from the MoS2 layer to the WS2 layer takes place within 50 fs after optical excitation, a remarkable rate for van der Waals coupled 2D layers. Such ultrafast charge transfer in van der Waals heterostructures can enable novel 2D devices for optoelectronics and light harvesting.

References in corpus (3)

• Anomalous Lattice Vibrations of Single and Few-Layer MoS2
• Measurement of the Optical Conductivity of Graphene
• Emergence of Superlattice Dirac Points in Graphene on Hexagonal Boron Nitride

Cited by in corpus (32)

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• Determination of band alignment in the single layer MoS2/WSe2 heterojunction
• Moiré excitons: from programmable quantum emitter arrays to spin-orbit coupled artificial lattices
• Efficient Interlayer Relaxation and Transition of Excitons in Epitaxial and Non-epitaxial MoS2/WS2 Heterostructures
• Interlayer Exciton Optoelectronics in a 2D Heterostructure p-n Junction
• Theory of optical absorption by interlayer excitons in transition metal dichalcogenide heterobilayers
• Ultrafast Exciton Dissociation and Long-Lived Charge Separation in a Photovoltaic Pentacene MoS2 van der Waals Heterojunction
• Observation of interlayer phonon modes in van der Waals heterostructures
• Interlayer coupling in commensurate and incommensurate bilayer structures of transition metal dichalcogenides
• Probing the inter-layer exciton physics in a MoS${}_2$/MoSe${}_2$/MoS${}_2$ van der Waals heterostructure
• Directional Interlayer Spin-Valley Transfer in Two-Dimensional Heterostructures
• Device physics of van der Waals heterojunction solar cells
• Interlayer coupling and gate-tunable excitons in transition metal dichalcogenide heterostructures
• Mutual Photoluminescence Quenching and Photovoltaic Effect in Large-Area Single-Layer MoS2-Polymer Heterojunctions
• Exciton mapping at subwavelength scales in two-dimensional materials
• Spatially Resolved Electronic Properties of Single-Layer WS${}_2$ on Transition Metal Oxides
• Photoresponse of atomically thin MoS2 layers and their planar heterojunctions
• Electronic and optical excitations of two-dimensional ZrS${}_2$ and HfS${}_2$ and their heterostructure
• Enhanced Light-Matter Interaction in Graphene/h-BN van der Waals Heterostructures
• Intrinsic p-type W-based transition metal dichalcogenide by substitutional Ta-doping
• Yb- and Er-doped fiber laser Q-switched with an optically uniform, broadband WS2 saturable absorber
• Strong Single- and Two-Photon Luminescence Enhancement by Nonradiative Energy Transfer across Layered Heterostructure
• Electric Field Tuning of Band Offsets in Transition Metal Dichalcogenides
• A facile synthesis method and electrochemical studies of hierarchical structured MoS2/C-nanocomposite
• Inter-layer charge transport controlled by exciton-trion coherent coupling
• Visualization of defect-induced excitonic properties of the edges and grain boundaries in synthesized monolayer molybdenum disulfide
• Observation of Ultralong Valley Lifetime in WSe2/MoS2 Heterostructures
• Charge photogeneration in few-layer MoS2
• MoS2 Heterostructure with Tunable Phase Stability: Strain Induced Interlayer Covalent Bond Formation
• Room temperature interlayer exciton valley polarization and valley Hall effect