First-Principles Study on the Structural and Electronic Properties of Monolayer MoS₂ with S-Vacancy under Uniaxial Tensile Strain.

Chenguang Yang,Minglin Li,Weidong Wang,Weibing Li,Liwen Bai

doi:10.3390/nano8020074

Abstract

Monolayer molybdenum disulfide (MoS2) has obtained much attention recently and is expected to be widely used in flexible electronic devices. Due to inevitable bending in flexible electronic devices, the structural and electronic properties would be influenced by tensile strains. Based on the density functional theory (DFT), the structural and electronic properties of monolayer MoS2 with a sulfur (S)-vacancy is investigated by using first-principles calculations under uniaxial tensile strain loading. According to the calculations of vacancy formation energy, two types of S-vacancies, including one-sulfur and two-sulfur vacancies, are discussed in this paper. Structural analysis results indicate that the existence of S-vacancies will lead to a slightly inward relaxation of the structure, which is also verified by exploring the change of charge density of the Mo layer and the decrease of Young’s modulus, as well as the ultimate strength of monolayer MoS2. Through uniaxial tensile strain loading, the simulation results show that the band gap of monolayer MoS2 decreases with increased strain despite the sulfur vacancy type and the uniaxial tensile orientation. Based on the electronic analysis, the band gap change can be attributed to the π bond-like interaction between the interlayers, which is very sensitive to the tensile strain. In addition, the strain-induced density of states (DOS) of the Mo-d orbital and the S-p orbital are analyzed to explain the strain effect on the band gap.

Highlights

Since the discovery of graphene, 2D materials such as boron nitride (BN), molybdenum disulfide (MoS2 ), and tungsten disulfide (WS2 ) have become one of the hot topics in the scientific community because of the fantastic physical properties and promising applications of these materials in flexible electronic devices [1]
It is different from the structure of graphene in that it has three atomic layers composed of one Mo layer plus two S layers on both sides, which are held together by van der
We investigate the structural and electronic properties of monolayer MoS2 with S-vacancy defects under tensile strain loading by using first-principles calculations

Summary

Introduction

Since the discovery of graphene, 2D materials such as boron nitride (BN), molybdenum disulfide (MoS2 ), and tungsten disulfide (WS2 ) have become one of the hot topics in the scientific community because of the fantastic physical properties and promising applications of these materials in flexible electronic devices [1]. Among the 2D materials mentioned above, MoS2 is one candidate for flexible electronic devices because of its good mechanical and electrical properties. The bulk of MoS2 belongs to the space group P63 /mmc. Surface of bulk MoS2 [2]. It is different from the structure of graphene in that it has three atomic layers composed of one Mo layer plus two S layers on both sides, which are held together by van der. Flexible electronic material will inevitably suffer bending

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Conclusion