Characterization of electrochromic tungsten oxide film from electrochemical anodized RF-sputtered tungsten films

Tungsten oxide (WO3) films prepared by annealing electrochemically anodized metallic tungsten (W) films deposited by radio-frequency sputtering were characterized. Tungsten oxide films of various morphology, crystallinity, and porosity can be prepared by carefully altering the anodization time (20–50 min) and annealing temperature (450–550 °C). The film obtained after 40 min of anodization, and that annealed at 500 °C shows the best electrochromic performance with optical modulation of 43.6% and coloration efficiency of 42.8 cm2/C. The effects of anodization time and annealing temperature on microstructure and electrochromic properties were addressed.