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Abstract: 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 (20–50min) and annealing temperature (450–550°C). The film obtained after 40min of anodization, and that annealed at 500°C shows the best electrochromic performance with optical modulation of 43.6% and coloration efficiency of 42.8cm2/C. The effects of anodization time and annealing temperature on microstructure and electrochromic properties were addressed. [Copyright &y& Elsevier]

Abstract: The Nb-doped WO3 films were deposited by e-beam co-evaporation method using ceramic WO3 targets and metal Nb slugs. The films were analyzed by glancing incident angle X-ray diffraction (GIAXRD), UV/visible spectrophotometer, electrochemical cyclic voltammetry, X-ray photoelectron spectroscopy (XPS). The as-prepared film is brown and amorphous in structure. The film has low transmission in optical visible region. The XPS results indicate that the as-deposited film is non-stoichiometric. By applying a negative potential, the as-deposited film does not show obvious electrochromic effect. However, the electrochromic properties of Nb-doped WO3 films are improved by post annealing treatment at 350, 400, and 450°C in oxygen atmosphere. The Nb-doped WO3 films transform into crystalline structure and become transparent after post annealing treatment. The energy band gap, optical modulation, and color efficiency increase with annealing temperature. [Copyright &y& Elsevier]