Tungsten Oxide Thin Film Photochromic Application

Tungsten oxide photochromic property has widely application prospects in optical information storage, optical control, optical switched, optical device, materials, optical information genetic material. Currently the use of tungsten oxide photochromic properties have been designed and manufactured a lot of practical application of devices, such as WO3 / TiO2 composite solar cells being used to split water, smart windows which have photochromic properties and electrochromic properties.

Optical recording and image storage

The use of photochromic compounds discolored when the different wavelengths of light irradiation intensity and color characteristics of repeated cycles, which can be made from computer memory storage element, to achieve the elimination process and memory information. Recording information density is very large, good fatigue resistance, can fast write and erase information. Amorphous WO3 being a KrF excimer laser wavelength for the next generation of 248 nm laser irradiation will become purple, wavelength be produced Nd-Y-Al garnet laser for the laser irradiation of 1.06 μm and can be changed into colorless. The study also found that the use of WO3 changes in the optical properties of the annealing process characteristics made a write-once optical recording disk, the data storage density can be up to maximum 25 GB. In addition WO3 under UV irradiation photosensitivity can be used to autoradiography holographic recording photographed. Painted WO3 thin film on transparencies layer, which is not sensitive to visible light, can change into a colored image in the UV irradiation. It has high resolution imaging method, no operator error and the image can be repeatedly recorded and eliminated.

Tunable optical band gap of photonic crystals

Photonic crystals are artificial structures showed permittivity in the space formed by periodically arranged. Like ordinary crystals, periodic photonic crystals are arranged with a band structure, photonic band gap may exist. Photonic band gap or band gap refers to a range of frequencies of electromagnetic waves, in this frequency range can not propagate in the photonic crystal where the frequency band is located in the almost non-destructive electromagnetic wave is able to propagate in the photonic crystal. The ratio of the dielectric constant of the band gap width and position of the photonic crystals are related. WO3 permittivity can be continuously changed in a wide range of light irradiation or under the influence of an electric field of the dielectric, and therefore the tungsten oxide templates to create a photonic crystal polystyrene inverse opal structures can be more effective to regulate the optical path.

Dye-sensitized solar cell

Dye-sensitized solar cell (DSSC) refers to use the dye-sensitized nanostructured porous thin film as anodic, according to the principle of photovoltaic, solar energy is directly converted into electrical energy in a semiconductor optoelectronic device. Photoelectric conversion efficiency and light anodic films as band gap have a great relationship, generally select band gap of 3.2 eV of TiO2 film as a light-anode. WO3 has a similar band structure with TiO2, except its band gap is relatively smaller. But the power of dye-sensitized solar cell is enough to make full use of tungsten oxide electrochromic thin film applied in smart window, display screen and so on. Also using tungsten oxide photochromic - electrochromic device is relatively simple in structure and environmental friendly.

UV protection film

Tungsten oxide is sensitive to ultraviolet, it can be made in to thin film and coated on the glass to protect human being from UV radiation. If WO3 thin film is coated on sunglasses, it can change color automatically to protect eyes under strong sunlight. Besides that WO3 can be used to detect the exist of UV and its strength.