In the Ta doped tungsten oxide electrochromic film, the amount of Ta doping affects the spectral modulation ability of the tungsten oxide film. The optical modulation amplitude ΔT of the tungsten oxide film is the difference of transmittance between the colored state and the discolored state.

Compared with tungsten trioxide film, the coloring efficiency of Ta doped WO3 film is improved. In other words, the electrochromic property of the film is improved, wherein the threshold value of the Ta doping amount is 15%, and excessive doping is not favorable for the film to show high electrochromic efficiency.

The cycle life of Ta doping WO3 film is an important parameter for the application of electrochromic materials and one of the important criteria for evaluating its performance.

What is the electrochromic performance of a Ta doped tungsten oxide film? Some experts have learned through the following experiments.

The electrochromic film of Ta doped tungsten trioxide nanoparticles has an amorphous structure, just like tungsten trioxide electrochromic film. Experts said that the tungsten trioxide film deposited at room temperature is an amorphous electrochromic film with a smooth surface, uniform texture and porosity.

Ta doped tungsten trioxide is a combination of Ta2O5 and WO3, which can combine the advantages of two materials to achieve higher mechanical and chemical compatibility, thereby improving the stability and using life of the device. In other words, the performance of the electrochromic film prepared from such composite material will be improved.

Ta doped tungsten oxide can be used to prepare electrochromic film. And the Ta doping tungsten oxide electrochromic films can be prepared by magnetron sputtering method to improve the electrochemical cycle stability of tungsten oxide electrochromic films.

Crystalline tungsten trioxide film can be prepared by magnetron sputtering deposition method and then by heat treatment. By magnetron sputtering deposition, an amorphous tungsten trioxide film is obtained, which is heated in air at 200°C, 250°C, 300°C, 350°C and 400°C and held for 30min for heat treatment. As the heat treatment temperature increases, the electrochromic properties of the amorphous tungsten trioxide film decrease. When the heat treatment temperature is higher than 350°C, the amorphous state is converted into a crystalline state.

WO3, or tungsten trioxide, can be used to prepare electrochromic film, and finally applied to architectural glass in the form of electrochromic glass, that is, smart window, to shield heat and save energy. Besides, as it has the characteristic of environmental protection, tungsten trioxide nano powder is more and more widely used in the production of electrochromic films.

MoO3 doping WO3 electrochromic film is darker in colored state and in bleached state than the pure tungsten trioxide film. This is because MoO3 itself is an electrochromic material with a color change similar to WO3. The colored state of MoO3 film is blue-violet and the bleached state is yellow. And the colored state of the pure tungsten oxide film is blue, and the bleached state is almost colorless or transparent.