Atmospheric pressure chemical vapor deposition of amorphous tungsten doped vanadium dioxide for smart window applications

Amorphous tungsten doped vanadium dioxide coatings were grown on SnO₂-precoated glass substrates using the atmospheric pressure chemical vapor deposition of vanadium (V) triisopropoxide and tungsten (VI) isopropoxide at 450°C without an oxygen source. The effect of N₂ flow rate through the tungsten's precursor bubbler was examined keeping the respective flow rate through the vanadium's precursor bubbler at 4 L min^-1 for a growth period of 30 min. They were characterized by x-ray diffraction, Raman and x-ray photoelectron spectroscopy, field-emission scanning electron microscopy and UV-vis/IR transmittance. The samples grown using 0.4 L min^-1 N₂ flow rate through the tungsten precursor's bubbler, showed the greatest reduction in transition temperature from 65.5 in granular VO₂ to 44°C in worm-like V_0.985W_0.015O₂ structures approaching that required for commercial use as a smart window coating.