Electronic structure and optical properties of alkali metal X (X=Li, Na, K, Rb, Cs) adsorbed in the Te vacancy-deficient molybdenum ditelluride system: A first-principles study

Abstract

In the framework of density functional theory, based on first principles, the plane wave pseudopotential technique was utilized to investigate the electrical and optical properties of MoTe2 adjusted by alkali metal X adsorption on Te vacancy defects (X[Formula: see text]=[Formula: see text]Li, Na, K, Rb, Cs). The adsorption of alkali metals on Te vacancy-deficient MoTe2 monolayers has been computationally analyzed. Charge transfer, electronic structure, and optical properties of alkali metal adsorption were systematically studied. It is shown that the MoTe2 bandgap is significantly reduced under Te vacancies. Te vacancies are frequently active sites in TMDs materials. With the adsorption of alkali metal atoms X (X = Li, Na, K, Rb, Cs) in the Te vacancy MoTe2 system, Li atoms have the most substantial geometrical deformation and the minor adsorption energy and can improve the adsorption properties more effectively. The MoTe2 system undergoes a change from semiconductor to metal after adsorption. Regarding optical properties, firm absorption and reflection peaks appeared, and a blueshift phenomenon was observed in the mountains. It is expected that these discoveries are likely to guide the use of molybdenum ditelluride in optoelectronics.