Nano cesium tungsten bronze that can transmit visible light but shield near-infrared (NIR) light is regarded as the best functional nanomaterial for producing office building thermal insulating film. And such heat insulating film has drawn much attention for the application of innovative energy-saving windows due to its selective shielding performance of solar light.

Nano cesium tungsten bronze for preparing office building thermal insulating film is a type of mixed valence state hexagonal tungsten bronze material, which has been successfully synthesized by solution and possesses excellent near-infrared (NIR) shielding properties. Similarly, mixed valence state tungsten suboxide (violet tungsten oxide, W18O49) also possesses excellent NIR shielding properties, and the improvement of shielding property can be successfully realized by decreasing the particle size.

Nano cesium tungsten bronze, or nano CsxWO3, is the optimal raw material for preparing sun room thermal insulating film that has superior performance over commercial ITO glass. The experts compared the transmittance and reflectance of CsxWO3 nanorods with those commercial ITO glasses. And it is found that the CsxWO3 synthesized from the water molecular controlled-release solvothermal process (WCRSP process) has superior performance over commercial ITO glass due to its stronger absorption properties both in NIR region and UV region.

Nano cesium tungsten bronze for nano heat insulating film can be prepared by water molecular controlled-release solvothermal process (WCRSP process) --- a new facile method to synthesize CsxWO3 nanorods possessing excellent NIR shielding ability.