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

Ruihao Sun,Dongwei Li,Xingshuang Zhang,Shiyu Sun,Guanchen Xu,Meng Gao,Xiu Liang,Hongyu Gong,Yong Li

doi:10.3390/nano12010164

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.

Highlights

Academic Editor: Daniele FazziTransition metal dichalcogenides (TMDCs) have attracted much attention as promising layer-like materials
2D transition metal dichalcogenides (TMDCs) with semiconductor properties represented by the monolayer MoS2 and WS2 show excellent electrical and optical properties, high switching ratio and large carrier mobility, which make them valuable for a wide range of applications in logic circuits, photodetectors, photovoltaic circuits, light-emitting diodes and other optoelectronic devices [6,7,8]
We present the surface charge transfer doping of the chemical vapor deposition (CVD)-grown monolayer MoS2 by using designed aggregation-induced emission (AIE) molecules formulated in low concentration solutions as organic dopants to selectively tune the optical and electrical properties of the CVD-grown monolayer MoS2

Summary

Introduction

Academic Editor: Daniele FazziTransition metal dichalcogenides (TMDCs) have attracted much attention as promising layer-like materials. 2D TMDCs with semiconductor properties represented by the monolayer MoS2 and WS2 show excellent electrical and optical properties, high switching ratio and large carrier mobility, which make them valuable for a wide range of applications in logic circuits, photodetectors, photovoltaic circuits, light-emitting diodes and other optoelectronic devices [6,7,8]. The doping engineering used in 2D TMDCs includes substitution doping [9,10], intercalation doping [11], electrostatic doping [12] and surface charge transfer doping (SCTD). Among these techniques, SCTD has the advantages of being effective with no lattice damage. The use of H2 O, O2 [15], NO2 , NH3 [16] and K [17]

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Conclusion