Tungsten trioxide is a η-type wide band gap semiconductor oxide (with the band gap of about 2.4~2.8eV), at low and room temperature, WO3 exist in the form of monoclinic and triclinic phase; whereas at high temperatures, the orthogonal and tetragonal phases will come into being. The ideal crystal structure of WO3 can be seen as consisting of six O atoms around the central atom W and form the octahedral of tungsten – oxygen [WO6], they are connected together via common vertices; there are many gaps between the octahedral to form the various channels, and these distribution channels serve as distribution channels and embedding position which are good body injection plasma of H+, Li + and other ions. Therefore, tungsten trioxide as the most classic electrochromic inorganic material, with its fast response, high coloring efficiency, high coloring  and achromatic contrast and other properties, is widely used in electrochromic devices, photochromic devices and intelligent display and other fields.

 

This article describes a method for preparing nano WO₃ electrochromic film as follows:

1. Add the resulting solutions in a reaction vessel, then put the source of tungsten target material in to the solution, ensure the solution is impregnating the target surface, then you may stir the solution uniformly with the using of a magnetic stirrer, wherein the source of tungsten target can be pure tungsten with the purity of higher than 99.9% or tungsten oxide ceramic target;

2. Adjust the optical path of the laser pulse laser beam, the laser beam is focused below the surface of the target material in a solvent, select the appropriate laser wavelength, energy and frequency, pulsed laser is turned in the liquid environment of the source of tungsten target ablation 1 to 2 hours;

3. The pulse laser is turned off after finished the pulsed laser ablation reaction, then a colloidal solution containing tungsten oxide nanoparticle is obtained, then aged at room temperature for 1-4 hours, with the laser ablation product and solution are further reacted;

4. Adjust the pH value of the solution after aging, and place a transparent conductive glass as an electrode in the solution, to carry out the laser electrophoretic deposition of the product after aged under acidic conditions for 5 to 60 minutes to prepare a nano tungsten trioxide film.