Electronic and Optical Properties of Monolayer WxMo1-xS2 Alloys: a First-principles Study
LIU Junnan1,2, SONG Shupeng1,2,*, HU Dongdong1, ZHOU Herong1, WU Run1
1 School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China 2 The State Key Laboratory of Refractory and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China
Abstract: First-principles calculations are employed on the electronic and optical properties of WxMo1-xS2(x=0,0.25,0.5,0.75,1) monolayer alloys under the direction of density functional theory calculations. The calculated results indicate that the band gaps of the alloys, which will be increased nonlinearly from 1.802 eV to 1.940 eV with the increase of W content, are all direct band gaps. It is shown in the calculated results of charge differential density that both the number of electrons lost by Mo atom and that of electrons gained by W atom increase gradually as W content climbs. The optical properties of the alloys can be tuned with the change of W content.With the increase of W content, the static dielectric constant gradually decreases, the absorption threshold of the imaginary part gradually increases, and the absorption edge moves to the high energy range. Compared with original Mo16S32, WxMo1-xS2 alloys have stronger absorption ability in the ultraviolet range (6—8.5 eV), while W12Mo4S32 and W16S32 alloys have higher absorption coefficient in the visible range (~3 eV), indicating in theory that the sort of the monolayer alloys can be applied to the detection of photoelectric signals in visible light and near ultraviolet range.
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2021, Vol. 35 
