Chemical and Electronic Repair Mechanism of Sulfur Defects in MoS$_2$ Monolayers

TL;DR

This study uses ab initio calculations to understand how sulfur defects in MoS₂ monolayers can be repaired chemically and electronically, revealing mechanisms involving thiol molecules and sulfur atoms that improve material properties.

Contribution

It provides a detailed atomic-level understanding of sulfur defect repair mechanisms in MoS₂ using density functional theory, highlighting the role of thiol molecules and sulfur adsorption.

Findings

Thiol molecules can re-insert sulfur into vacancies.

Disulfide formation on MoS₂ surface mitigates defect effects.

Sulfur adsorption restores electronic properties.

Abstract

Using {\em ab initio} density functional theory calculations, we characterize changes in the electronic structure of MoS$_{2}$ monolayers introduced by missing or additional adsorbed sulfur atoms. We furthermore identify the chemical and electronic function of substances that have been reported to reduce the adverse effect of sulfur vacancies in quenching photoluminescence and reducing electronic conductance. We find that thiol-group containing molecules adsorbed at vacancy sites may re-insert missing sulfur atoms. In presence of additional adsorbed sulfur atoms, thiols may form disulfides on the MoS$_{2}$ surface to mitigate the adverse effect of defects.