The Feasibility of Tungsten-Doped VO2 Films on Soda-Lime Glass with Low Thermal Budget by High Density Plasma Source for Smart Windows

Thermochromic W-doped VO2 thin films on soda-lime glass are successfully fabricated by co-sputtering technique using a high density plasma source, which is equipped by high power impulse magnetron sputtering (HIPIMS). A post-rapid thermal annealing of 500 degrees C is performed for the purpose of low thermal budget. The effect of doping amount of tungsten on thermochromic properties such as transmittance and transition temperature are addressed. The transition temperature can be lower down to 30 degrees C with a small amount of 4.5% tungsten added in VO2 nanocrystals. A solar regulation efficiency, Delta T-sol = 10% is achieved at thicker TiO2 thickness. The competition of secondary phase of V2WO7.5 and oxygen-rich phase of V2O5 under different O-2/Ar ratio is studied. The crystalline behavior of monoclinic phase is examined by X-ray diffraction (XRD) pattern and high resolution transmission electron microscope (HR-TEM). The good endurance property ensures the feasible use for the energy-saving applications.