Facile Doping in Two-Dimensional Transition-Metal Dichalcogenides by UV Light

Abstract

Two-dimensional (2D) materials have been emerging as potential candidates for the next-generation materials in various technology fields. The performance of the devices based on these 2D materials depends on their intrinsic band structures as well as the extrinsic (doping) effects such as surrounding chemicals and environmental oxygen/moisture, which strongly determines their Fermi energy level. Herein, we report the UV treatments on the 2D transition-metal dichalcogenides, to controllably dope the samples without damaging the crystal structures or quenching the luminescence properties. More surprisingly, both n-type and p-type doping can be achieved depending on the initial status of the sample and the UV treatment conditions. The doping mechanisms were elaborated on the atomic scale with transmission electron microscopy and ab initio calculations. The facile doping by UV light has potential to be integrated with photolithography processes, aiming for the large-scale integrated device/circuits design and fabrications.

Redox Photochemistry on Van Der Waals Surfaces for Reversible Doping in 2D Materials

“…Such stable vdW surface oxidation can be clearly observed in 1L‐ReS 2 and 1L‐ReSe 2 , however absent in 1L‐MoS 2 and graphene with our experimental conditions, where the defects are involved. [ 21 ] In MoS 2 , the oxygen radicals could easily generate S vacancies instead of SO bonding formation. Our DFT result shows the S vacancy formation energy of 1L‐MoS 2 (−3.25 eV) is lower than that of 1L‐ReS 2 (−2.55 eV), thus more likely to form vacancies during UV treatment in 1L‐MoS 2 (see Figures S21 and S22, Supporting Information), precluding the similar vdW surface oxidation in MoS 2 .…”

Defect Engineering in Ambipolar Layered Materials for Mode‐Regulable Nociceptor

“…Unlike most irreversible doping effects produced by chemical methods or surface charge transfer doping, this photo‐induced doping phenomenon gradually recovered to its initial state within 10 min (Figure S3, Supporting Information). [ 33–36 ] Interestingly, it was found that the recovery process could be promoted by immersing the device in dry air, indicating the potential occurrence of photo‐induced adsorption and desorption of molecules, e.g., oxygen. [ 16,33 ] The extracted current variation ( I irradiation / I initial ) as a function of gate voltage shown in Figure 1e indicates a more distinct change under negative electrostatic gating, which is beneficial for exploration of the dynamic variation.…”

Vanadium Dopants: A Boon or a Bane for Molybdenum Dichalcogenides‐Based Electrocatalysis Applications

“…In general, doping can occur via either direct substitution of atoms or via interstitial sites amidst atoms found within the crystal lattice or through intercalation amidst layers in layered TMDs ( Figure ). [ 28,29 ] Doping of TMDs can possibly enhance their electronic properties and the density of active sites, hence improving their catalytic activities. For instance, studies have reported that when TMDs are doped with metallic heteroatom, their differential free energy of hydrogen adsorption, Δ G H get altered and proton‐transfer kinetics were accelerated, which are beneficial for hydrogen evolution reaction (HER).…”