Zr and W Co-doped VO₂ thin films with improved luminous transmittance and transition temperature

This work reports on successful preparation of thermochromic zirconium and tungsten co-doped vanadium dioxide thin films. The impact of Zr and W co-doping of the thermochromic VO2 thin films on the luminous transmittance and transition temperature of the films is presented. The structural phases and surface morphology of the films were analyzed using the x-ray diffraction and atomic force microscopy, respectively. Two points probe and UV/VIS/NIR Spectrometer were utilized to analyze the films' electrical and optical properties, respectively. Rutherford backscattering spectroscopy (RBS) was employed to identify the elemental compositions of the films. It was found that Zr and W co-doping of VO2 thin films with similar to 0.3 at% Zr and similar to 0.95 at% W concentration improves luminous transmittance to about 48.4% compared to 40.5 and 26.2% for pristine VO2 and VO2:W films, respectively. The transition temperature of the co-doped films was lowered to 36 C-degrees, compared to 64.8 and 44 degrees C for VO2 and VO2:W thin films, respectively. This study demonstrates that VO2 thin films may be effective for smart windows applications if W-doped VO2 films include a regulated proportion of Zr.