Surface Charge Transfer Doping of MoS2 Monolayer by Molecules with Aggregation-Induced Emission Effect

Abstract

Surface charge transfer doping has attracted much attention in modulating the optical and electrical behavior of 2D transition metal dichalcogenides (TMDCs), where finding controllable and efficient dopants is crucial. Here, 1,1,2,2-tetraphenylethylene (TPE) derivative molecules with aggregation-induced emission (AIE) effect were selected as adjustable dopants. By designing nitro and methoxyl functional groups and surface coating, controlled p/n-type doping can be achieved on a chemical vapor deposition (CVD) grown monolayer, MoS2. We investigated the electron transfer behavior between these two dopants and MoS2 with fluorescence, Raman, X-ray photoelectron spectra and transient absorption spectra. 1,1,2,2-Tetrakis(4-nitrophenyl)ethane (TPE-4NO2) with a negative charge aggregation can be a donor to transfer electrons to MoS2, while 1,1,2,2-Tetrakis(4-methoxyphenyl)ethane (TPE-4OCH3) is the opposite and electron-accepting. Density functional theory calculations further explain and confirm these experimental results. This work shows a new way to select suitable dopants for TMDCs, which is beneficial for a wide range of applications in optoelectronic devices.

Molybdenum Disulfide Flakes as Platforms for the Photoconversion of 4-Nitrothiophenol

“…Energy diagram of the probable mechanism of the photoinduced charge transfer between 4-NTP molecules and monolayer MoS 2 flakes. The energy band structures of MoS 2 , 4-NTP, and DMAB are adapted from refs − . HOMO stands for the highest occupied molecular orbital.…”

Surface Wettability-Mediated Enhancement of Hydrogen Evolution Reaction Performance in Electron-Doped MoS2 Monolayers

“…Doping is one of the effective energy level modulation strategies for improving HER performance in semiconducting catalysts. ,− The energy level modulation in MoS 2 catalysts significantly modifies both charge carrier concentration and potential barrier at the junction, and charge exchange kinetics with electrolyte, which is correlated with catalytic behavior in HER . Thus, various doping strategies such as atomic substitution, self-assembled monolayers (SAM), and ion implantation have been exploited to donate and withdraw the electron in MoS 2 monolayers, which was directly related to HER dynamics in semiconducting catalysts. − However, in the case of surface-modified doping strategies, not only the charge carrier concentration but also surface wettability of electrolysis catalysts can be modified through the doping, which significantly affects the reaction rate in HER. − …”

Defect-Rich Monolayer MoS2 as a Universally Enhanced Substrate for Surface-Enhanced Raman Scattering

“…Here, for the first time, we use experiments and theory to investigate the Raman enhancement effect of monolayer MoS 2 before and after the presence of surface defects. In this paper, large-scale, highly crystalline samples were prepared under the precise control of the chemical vapor deposition (CVD) method with sulfur powder and electroplated molybdenum foil as precursors of the monolayer MoS 2 and with SiO 2 /Si as substrates [ 40 , 41 , 42 ]. Indeed, due to the strong fluorescence background and inefficient CT, it is difficult to visualize the SERS signal in perfect MoS 2 monolayers, especially when the surface contains low concentrations of detected molecules.…”