The thin film coating will change the color of the film due to the absorption of external energy. This material is called an electrochromic material. The electrochromic effect of the tungsten trioxide film is closely related to its microstructure.
Yellow tungsten oxide, tungsten trioxide, is a typical representative of inorganic electrochromic materials. The principle is to adjust the light transmittance by changing the size of the current to achieve dimming from transparent to opaque.
Regarding the electrochromic mechanism of WO3 films, the current intervalence transition theory proposed by Faughnan is that due to the effect of an external electric field, electrons and cation minerals are simultaneously injected into WO3 from both sides of the film, and the electrons are captured by W atoms to form a localized state. The ion M+ resides in this area to form a dark blue tungsten bronze compound Mx WO3. There are W ions of different valence states in Mx WO3. The transition of electrons between adjacent W atoms of different valence states causes the color of the WO3 film to change.
The yellow tungsten oxide electrochromic film utilizes the electrochromic properties of tungsten trioxide and is prepared by physical vapor deposition, chemical vapor deposition, electron beam evaporation and other methods. It has low cost, good cycle reversibility and good optical properties. , fast color change and other advantages, it can be used in smart windows, architectural glass, car rearview mirrors and other fields.
