The influence of sol–gel processing on the electrochromic properties of mesoporous WO3 films produced by ultrasonic spray deposition

High performance mesoporous tungsten oxide films were deposited by ultrasonic spray deposition using templated sol–gel chemistry. The dynamics of both sol preparation and hydrolysis were investigated by UV–vis spectroscopy. A stable sol was formed after 12h, while optimum electrochromic performance was obtained for 12h of hydrolysis. Electrochromic performance is strongly correlated to the annealing conditions, with optimized films displaying coloration efficiency >50cm2/C and switching times 50cm2/C), modulation (>75%), switching times (~6s).•The materials chemistry of the sol–gel process is evaluated by dynamic UV–vis spectroscopy.•The material properties of the resulting mesoporous tungsten oxide are extensively characterized by FTIR, Raman, TEM, SAD and correlated to electrochromic performance.