| Abstract
| - Electrochromic tungsten oxide film was fabricated by a new soft chemistry route, in whichthe transparent conducting glass substrate was successively dip-coated with poly(acrylicacid) (PAA) and ammonium tungstate solutions. The as-coated composite layer of PAA/(NH4)2WO4·nH2O was dried at a low temperature (100 °C), and the ammonium tungstate componentwas polycondensed by acid treatment in 1 N HCl to form an electrochromic PAA/WO3 film.Transmission electron microscopy showed that the PAA/WO3 film contains regularlydispersed WO3 grains with an average size of ∼5 nm. According to the Auger depth profileanalysis, the relative content of W, O, and C was quite homogeneous along the height offilm. Depending on the concentration of PAA coating solution (1.0−3.0 wt %), the thicknessand tungsten oxide content of the film were found to vary; therefore, the electrode propertyof the PAA/WO3 layer could easily be controlled. By using a 2.5 wt % PAA solution, anoptimum electrochromic function was achieved with a coloration efficiency of ∼38 cm2/Cand a cycle life of >11 000 under operation with Q = 12.5 mC/cm2.
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