Since tungsten oxide film was found to have electrochromic properties, it has been extensively studied. However, the performance of a single substance-induced color film are still unable to meet the practical requirements, so many researchers have done a lot of researches to improve the electrochromic properties of thin film.
TiO2 thin film is used as ion conductive layer in the tungsten oxide thin film electrochromic device, by doping it into WO3 thin film can improve its electrochromism. Most researchers use sol-gel method to producing TiO2-doped tungsten oxide thin film, but the quality is poor and easy to crack, the doping amount is limited.
For pure tungsten oxide film, composite tungsten oxide and doped tungsten oxide thin film, the environmental stability of transmittance curve improves gradually. The roughness of the film enlarges due to the doping of TiO2 and Ag. Due the presence of TiO2, WO6 octahedra will be subsitituted by TiO6, result in disorder of polyanion structure, the doped thin film would have a stable amorphous state, increases the content of W4 + in thin film. In the mean time the increasing roughness also enhance the capacity of the Li ion implantation, thereby improving the efficiency of organic color film. Furthermore, since the silver layer is sputtered by magnetron method, the electrochromic efficiency of tungsten oxide thin film improves by 52.85%.