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

Monoclinic vanadium dioxide is a thermochromic material for advanced applications to smart optoelectronic devices. However, the poor visible-light transmission and high phase transition temperature (Tc) of VO2 hinder its practical use. Our first-principles calculations show that group IV elements (Si, Ge, Sn, Pb) doping may be an efficient way to reduce the Tc of VO2, 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. In addition, group IV elements (Si, Ge, Sn, Pb) doping can improve the absorption and transmittance of light in the low energy region, favoring the efficient utilization of sunlight in the infrared region. Our findings would provide a useful guidance for fabrication of high quality VO2 based thermochromic materials.