Microstructure of Laser-Fired, Sol−Gel-Derived Tungsten Oxide Films

Half-micron-thick tungsten oxide films were deposited by the sol−gel method onto indium tin oxide (ITO) coated soda lime silicate substrates. Following a 100 °C prebake, the samples were fired with a carbon dioxide laser at a variety of power densities and translation speeds. The laser-fired tungsten oxide films were characterized by spectrophotometry, electrochemistry, multiangle ellipsometry, and transmission electron microscopy and compared to similar furnace-fired films. The data showed an increase in electrochromic response with increased firing temperature up to the point where crystallization of the tungsten oxide retarded electrochromic response. A window with graded electrochromic properties was made by laser firing.