Energetics, electronic and optical properties of X (XÂ =Â Si, Ge, Sn, Pb) doped VO2(M) from first-principles calculations

Group IV elements (Si, Ge, Sn, Pb) doping VO2 not only can improve the absorption and transmittance of light in the low energy region, but also could reduce the phase transition temperature (Tc), which is coupled with the changes in the geometry and electronic structures, i.e. the decrease in Tc is associated with the correlation between the volume and the β angle, and the variable band gaps between eg and t2g are narrowed by 0.05-0.37 eV after doping.138