Observation of Hole Transfer in MoS₂/WS₂ Van der Waals Heterostructures

Abstract

The ultrafast dynamics for the formation/recombination of interlayer exciton and charge transfer in MoS2/WS2 heterostructures are studied by pump–probe measurements combined with density functional theory simulations. MoS2/WS2 heterostructure forms a type-II band alignment where the conduction band minimum is in MoS2 and the valance band maximum locates in the WS2 layer, respectively. By modulating the transient absorption configurations, a significant hole transferring process is observed from the MoS2 layer to the WS2 layer, instead of electrons moving oppositely, forming spatially interlayer excitons with longer lifetimes than that occurring in individual monolayers in hundreds of femtoseconds. This work gives a comprehensive understanding of ultrafast exciton dynamics of MoS2/WS2 and confirms its potential for realizable gate-controllable optoelectronics.

Exciton Dissociation, Charge Transfer, and Exciton Trapping at the MoS2/Organic Semiconductor Interface

“…Quenching of the PL spectrum alludes to the presence of a new nonradiative pathway such as charge transfer processes. 16,20,23,33 To understand charge transfer processes at the ANNP/ MoS 2 heterostructure, TA spectroscopy was performed. First, 1L-MoS 2 was excited at 532 nm with a fluence of 8.45 μJ/cm 2 which resulted in an excited carrier density of 5.07 × 10 11 cm −2 .…”

“…The PL spectra of ANNP/MoS 2 shifted 5 nm to longer wavelengths and was quenched relative to MoS 2 (Figure c). Quenching of the PL spectrum alludes to the presence of a new nonradiative pathway such as charge transfer processes. ,,, …”

Interfacial Charge Transfer in Atomically Thin 2D Transition-Metal Dichalcogenide Heterostructures

“…15,21−25,19,26−29 Similarly, broadening and red shift of excitonic transitions in absorption spectra of the heterostructure in comparison to separate monolayers, potentially due to additional relaxation channels, have also been attributed to charge transfer. 23,25,[30][31][32]29 To study the kinetics of charge-transfer dynamics in TMD/ TMD heterostructures, ultrafast pump−probe transient spectroscopy is commonly used. As mentioned before, this is because excitons in TMDs typically decay in picoseconds, especially at room temperature.…”

“…Instead, they suggested that charge transfer takes place between the two components at the type II interface. PL quenching from both constituent layers in TMD/TMD heterostructures is frequently interpreted as a sign of charge transfer. ,− ,,− Similarly, broadening and red shift of excitonic transitions in absorption spectra of the heterostructure in comparison to separate monolayers, potentially due to additional relaxation channels, have also been attributed to charge transfer. ,,− , …”

Designing and Development of AsP–GeY (S; Se) In-Plane and van der Waals Heterojunction-Based Photonic Devices for Wavelength Tuning

“…20,21 Consequently, this study focuses on two-dimensional materials with diverse band gaps and facile manipulation in heterojunction engineering. 22,23 Following graphene, black phosphorus (BP) has gained widespread use in developing various functional devices due to its excellent physical and chemical properties. 24,25 However, the instability of BP in ambient air severely limits its potential as a nanoelectronics device.…”