The present invention relates to a tungsten oxide film and a method of making the film. The tungsten oxide film has greater than about 85% optical modulation across the visible spectrum. Furthermore, the film may be applied to a substrate that is not heated.
GOVERNMENT LICENSE RIGHTS
 This invention was made with government support under grant number DMR-0820518 awarded by the National Science Foundation and Contract No. DE-AC36-08GO28308 between the United States Department of Energy and the Alliance for Sustainable Energy, LLC, the Manager and Operator of the National Renewable Energy Laboratory. The Government has certain rights in the invention.