Equally Efficient Interlayer Exciton Relaxation and Improved Absorption in Epitaxial and Nonepitaxial MoS₂/WS₂ Heterostructures

Abstract

Ridge National Laboratory, Oak Ridge, Tennessee 37831 § These authors contribute equally. AbstractSemiconductor heterostructures provide a powerful platform to engineer the dynamics of excitons for fundamental and applied interests. However, the functionality of conventional semiconductor heterostructures is often limited by inefficient charge transfer across interfaces due to the interfacial imperfection caused by lattice mismatch. Here we demonstrate that MoS 2 /WS 2 heterostructures consisting of monolayer MoS 2 and WS 2 stacked in the vertical direction can enable equally efficient interlayer exciton relaxation regardless the epitaxy and orientation of the stacking. This is manifested by a similar two orders of magnitude decrease of

Photo-tunable transfer characteristics in MoTe2–MoS2 vertical heterostructure

“…6b) make interlayer electric dipoles, which could be the permanent one. 13,14,45 Nevertheless, this will give rise to a strong interlayer coupling, and perhaps shift-in the trenches of the transmission spectra to the lower-energy range values (which is~1.8 eV, in this case). Even though both classical and DFT-NEFG calculations qualitatively support our observation, a complete understanding of the transformation of the dip need further theoretical work.…”

Optoelectronic Devices Based on Atomically Thin Transition Metal Dichalcogenides

“…As the doping concentration in the monolayer sheets is determined by extrinsic factors, a gate voltage is needed to tune the stack to a regime in which a vertical p-n junction is formed. Charge transfer between individual TMD sheets was found to be ultrafast (<100 fs) and highly efficient (almost 100%) [36,37,[101][102][103]. The photovoltaic properties of various bulk and thin film TMD crystals have been studied since the 1980s [95].…”

MoS2/WS2 Heterojunction for Photoelectrochemical Water Oxidation

“…The heterojunction exhibits photocurrent and incident-photon-to-current-efficiencies (IPCE) 10 times 6 higher than the films comprised of the individual constituents. We attribute this to the more efficient exciton dissociation enabled by the creation of atomically thin p-n junctions analogous to MoS 2 /WS 2 bilayer heterostructures grown via CVD, 29,30 which can occur at faster timescales than the charge carriers recombination in individual WS 2 and MoS 2 layers. 31 The charges separated states in the bulk heterojunction have also been predicted to be long-lived despite the close contiguity of electrons and holes, increasing the chance of the water oxidation reaction to occur.…”