
Nano yellow tungsten oxide may be applied for the preparation of thermal insulation film. And this type of heat-insulating film may show its color by light irradiation with suitable energy. The photochromic mechanism of yellow tungsten oxide film can be expressed by the following equation: WO3+hv→WO3*+e-+h+ h++1/2H2O→H++1/4O2 WO3+xe-+xH+→HxWO3 When the yellow tungsten oxide film is irradiated with light, electrons e- and holes h+ are generated, and the photogenerated electrons enter the conduction band of the yellow tungsten oxide. The photogenerated…