First-principles study on the properties of Cu-doped in 2H-WSe₂

The structural, mechanical, thermodynamic and electronic properties of Cu substitution for W and Se as well as intercalated Cu in 2H-WSe₂ have been investigated by first-principles calculation. The stability of the doped structures is inferior than the pure 2H-WSe₂ and CuW₇Se₁₆ is unstable according to the phonon spectrum. After doping, the elastic moduli decrease for both Cu substitution structures, but increase for the intercalated structure. Cu doping can greatly affect the brittle property because the substituted structures exhibit a ductile property while the intercalated structure still exhibits a brittle property. They are all anisotropic, and CuW₇Se₁₆ exhibits the largest degree of anisotropic among them. Cu substitution can effectively reduce the Debye temperature and minimum thermal conductivity, in which CuW₇Se₁₆ has the lowest values. Cu doping transformed the semiconductor nature to semimetal. All crystals are non-magnetic and new covalent bonds are formed for Cu-doped structures.