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Apr 30, 2020

ACS Spring 2020 National Meeting & Expo

Crucial role of many-body van der Waals interaction in understanding the stability of point defects in monolayer MoS2

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Defects

Monolayer

Many-body dispersion

Absorption

Abstract

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30

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Abstract

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Keywords

Defects

Monolayer

Many-body dispersion

Absorption

Abstract

<br/>The present study investigates the stability of native point defects in MoS2 monolayer by first-principles based approach under the framework of density functional theory (DFT). Owing to its abundance and the property of band gap transition from indirect to direct on going from bulk to single-layer, MoS2 monolayer establishes a huge potential in semiconductor and optoelectronic industry. The synthesis or extraction of an element observes the presence of native defects, which becomes significant in exfoliation of different layers. The harnessing of defect states that tune the monolayer to required band gap for photovoltaics is an important approach. We have initiated our study by obtaining the phase diagram that shows the most stable defect states. The defects with minimum Gibbs free energy of formation are the stable states. We have considered three vacancies and five antisites in our system, with the factor of two-body and many-body van der Waals (vdW) interactions. Inclusion of many-body vdW interaction, which have posed a significant change in the pattern of stable defects, is necessary for realistic analysis. We, therefore, report the stable defect states as observed by HSE06 functional under many-body vdW interactions as, -2 and +2 charged states of S and Mo vacancies, -2 charged state of SMo antisite and +2 charged state of S2Mo antisite. These defect states have significant concentration in the finite temperature range of 50K-1000K. Defect analysis at finite temperature conditions is achieved by ab-initio atomistic thermodynamics along with the DFT input. Further, the -2 charged state of SMo antisite and +2 charged state of S2Mo antisite have tuned the band gap of MoS2 monolayer in the range of 1.1 – 1.8 eV. These states have shown optical response in the visible region, hence increasing the absorption capability of MoS2 monolayer.

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© Copyright 2019 Morressier GmbH.
All rights reserved.