Preparation Method of Zinc Tungstate Electrochromic Composite Film

Electrochromism refers to a stable and reversible change in the color or transmittance of a material under the action of an applied voltage or electric field. At present, electrochromic materials are considered to be one of the most promising smart materials, and it is expected to have great potential application value, such as smart window, automobile anti-glare rearview mirror and electrochromic display.

Among many electrochromic materials, tungsten oxide is the most common inorganic cathode electrochromic material, which has the advantages of low cost and non-toxic properties, and it is considered to be a material with great potential. The common preparation methods of the tungsten oxide film include chemical vapor deposition, radio frequency sputtering, sol-gel method, etc. The pure tungsten oxide film prepared by these methods tends to be relatively dense in structure and low in chemical activity, and ion or electron migration Affected, the spectral modulation amplitude is not high enough, the response time is long, and the color change efficiency is not high.

The small-sized nanocrystals and the amorphous tungsten oxide composite form a nanocrystalline/tungsten oxide composite film with a mosaic structure, and the nanocrystals form a mosaic structure in the tungsten oxide matrix, which can form a heterojunction in the film, where the nanocomposite effect has been enhanced. Electrochromic properties of tungsten oxide. The specific steps for preparing the zinc tungstate electrochromic composite film material are as follows:

Step (1): 0.5 g of soluble ZnO nanocrystalline powder is ultrasonically dispersed and dissolved in 10 mL of water to form an aqueous solution of ZnO nanocrystals;

Step (2): adding 2 g of ammonium metatungstate to the obtained ZnO nanocrystal aqueous solution, and ultrasonically obtaining a composite solution;

Step (3): sequentially adding 3 mL of ethanol and 2 mL of PEG600 to the obtained composite solution, and ultrasonically treating;

Step (4): the solution obtained in the step (3) is spin-coated on the cleaned ITO substrate by a spin coater; the spin coating speed is 500r/min, the gelling time is 5s, and then the rotation speed is 3000r/min, and the gelling time is 20s;

Step (5): The wet film prepared in the step (4) is first heat-treated in an air atmosphere, the heat treatment temperature is 350 ° C, and the temperature retention time is 60 min, and a zinc tungstate nanocomposite film is obtained.

The prepared zinc tungstate nanocomposite film has a nanocrystalline mosaic structure. The electrochromic spectral modulation performance of the zinc tungstate nanocomposite film has a spectral modulation amplitude of 54% at 633 nm. The electrochromic coloring time of the zinc oxide-tungsten nanocrystalline composite film is 10.8s, and the fading time is 2.6s. It exhibits excellent electrochromic spectral modulation performance and faster electrochromic response speed, and can be applied to the field of smart glass.

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