Enhance the interlayer coupling and modify the properties through Janus WSeTe

The surface modification of Te element is feasible in experiment, based on this, we replaced a layer of Se atoms of WSe2 bilayer with Te atoms. By using first-principles calculations, we learned that the properties of WSe2 bilayer will be significantly changed after tellurization. Due to structural configuration and Coulomb ion-dipole interaction, the interlayer distance of WSeTe/WSe2 heterostructure (HS) is reduced compared with WSe2 bilayer, leading to the stronger interlayer coupling and a smaller bandgap (1.50 eV). The bandgap of WSeTe/WSe2 heterostructure will decrease by more than 50% under 4% tensile strain, and the bandgap is continuously adjustable under 1-4% tensile strain. After tellurization, the optical absorption will be enhanced by 43% in the 547-800 nm wavelength range. The absorption intensity will be further enhanced by about 20% in the 413-578 nm wavelength range under 4% tensile strain. The WSeTe/WSe2 heterostructure also possesses smaller work function compared with that of WSe2 bilayer, which will enable improved photodetection and photoresponse time. This work expounds the influence of telluride on the properties of WSe2 bilayer, including interlayer coupling, electronic and optoelectronic properties, providing a basis for the construction of related highperformance optoelectronic devices.