Facile solution-grown mo-doped vanadium dioxide thermochromic films with decreased phase transition temperature and narrowed hysteresis loop width

Molybdenum (Mo) doped vanadium dioxide (VO2) (V_1-xMo_xO₂) thermochromic thin films with different Mo concentrations on borosilicate glasses were successfully synthesized via a facile and economic solution-based deposition method. The influences of substitutional doping with Mo dopants on the crystal structure and film morphology of VO₂ were evaluated. All of the films were confirmed to be pure monoclinic crystalline phase of VO₂ and no molybdenum oxides formed, suggesting the formation of a homogeneously dispersed solid-solution. The particle sizes and root-mean-square (RMS) roughness level obviously decreased upon Mo doping. V_1-xMo_xO₂ films exhibited low metal-semiconductor transition (MST) temperature (T_c) and retained the excellent switching property at near-infrared region simultaneously. The rate of change of Tc with Mo doping reached as high as ~10°C/at.%. The reduced T_c may be attributed to the disruption of homo-polar V⁴⁺-V⁴⁺ bonding after the incorporation of Mo atoms in VO₂ octahedron configuration. V_1-xMo_xO₂ thin films exhibited narrower hysteresis loop width compared to undoped VO₂, which show the promise for promoting practical implementation of VO₂-based thermochromic fenestration.