Electrochromic Glass Tungsten Thin Oxide Films Preparation

Building energy consumption generally accounts for more than one third of the total social energy consumption. At the same time, building energy contributes up to 25% of the world's greenhouse gas emissions, and is one of the major greenhouse gas emission reduction households. Glass windows are the main channel for building to exchange light and heat with the outside world, and 50% of building energy consumption is carried out through glass windows. The heat absorption of building exterior walls also aggravates the phenomenon of heat island in urban center.

Therefore, building energy conservation will play a decisive role in reducing greenhouse gas emissions. Similarly, energy-saving windows or exterior surfaces of mobile devices such as automobiles will contribute to comfort, energy saving and emission reduction.

Tungsten oxide with infrared barrier function is the main material for electrochromic glass. The valence composition of tungsten in tungsten oxide films includes + 6 valence tungsten ion and + 5 valence tungsten ion. Tungsten oxide film has high transmittance in visible region, but low transmittance in infrared region, which means it has good infrared barrier function. In addition, the matrix and the first protective layer on both sides of tungsten oxide film can prevent further oxidation of tungsten oxide and improve the corrosion resistance, which can greatly improve the service performance of tungsten oxide film.

The preparation process of tungsten oxide thin films includes:

1.Soak ordinary glass in detergent solution for several minutes, then brush the surface with a brush to remove grease and impurities on the glass surface. Rinse the glass with clean water, remove the residual detergent, then rinse with deionized water, remove the impurity ions on the surface, and use high-pressure dry air to dry.

2.The background of magnetron sputtering instrument is pumped to 10-5 order of magnitude to start sputtering. The tungsten oxide sputtered by DC power supply is set at 100W, the target material is high purity tungsten metal target, the gas is mixed with Ar and O₂, the purity is better than 99.9%, the proportion of oxygen is 5%, and the pressure is controlled at 0.5Pa during sputtering.

3.The sputtering silicon nitride is made of radio frequency power supply, power set at 100W, target material is made of silicon target of general purity, gas is mixed with Ar and N₂, purity is 99%, ratio is 1:1, sputtering pressure is controlled at 0.5Pa, pre-sputtering for 10 minutes. Formal sputtering, sputtering silicon nitride, thickness of 100 nm, sputtering tungsten oxide, thickness of 150 nm, sputtering silicon nitride, thickness of 100 nm, sputtering finished;

4.After sputtering, the glass plate is removed and annealed in a rapid annealing furnace. The heating rate is 4 /s, the target temperature is 500 and the heat preservation time is 2.5 min. After heating, it is cooled naturally in the air.

Using magnetron sputtering technology, tungsten oxide thin films with energy-saving effect were obtained on glass, transparent ceramics, silicon and metal sheets, including: matrix and tungsten oxide thin films with infrared barrier function formed on the surface of matrix.

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