Electrochromic Film with Core-shell Structure of Amorphous Crystalline Tungsten Trioxide

Electrochromism refers to the phenomenon that the optical properties of materials change reversibly under the action of external electric field. Electrochromism only needs a small voltage (about 2V) to work. In the open circuit state, it can keep the original color or fading state unchanged, so it consumes less energy.

At present, the core-shell structure composites of tungsten trioxide mainly involve the core-shell structure design of tungsten trioxide, titanium dioxide, zinc oxide nanorods and so on. The core-shell structure of tungsten trioxide nanowires as a framework can play the advantages of its own crystal amorphous structure, and improve its loop performance through the structural characteristics.

The preparation method of amorphous crystalline tungsten trioxide core-shell structure electrochromic film includes the following steps:

1)The tungstic acid is dissolved in the aqueous solution of hydrogen peroxide, and water is added to prepare a tungstic acid peroxide solution with a tungsten concentration of 1-5mol / L. The tungstic acid peroxide solution is coated on the conductive surface of the conductive substrate to obtain the conductive substrate covered with a seed layer;

2)Dissolve the tungsten source in water, adjust the pH value to 1-3.5, add ammonium sulfate to form precursor solution, fix the conductive substrate covered with crystal seed layer in the reactor, add the precursor solution to the reactor, react for 4h-10h at 150 ℃ - 250 ℃, take it out and obtain the tungsten trioxide nanowire array film;

3)Dissolve the tungsten source in water, drop hydrogen peroxide, adjust the pH value to 0.5-3, and form the electrodeposition solution. Use the constant voltage method to electrodeposit the amorphous tungsten oxide film electrode prepared in step 2) to obtain the amorphous / crystalline tungsten oxide core-shell structure electrochromic film.

The electrochromic tungsten oxide film with nanowire array morphology was prepared on various substrates (such as ITO conductive glass, ITO / Pet flexible conductive substrate, glass and metal, etc.) by combining hydrothermal and electrodeposition methods, and then amorphous tungsten oxide film was formed on the surface of tungsten oxide nanowire by electrodeposition. Moreover, the preparation process is simple, the nano array structure of the film can be easily controlled, the manufacturing cost is low, and it is easy to achieve large area growth.

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