A note on fast protonic solid state electrochromic device : NiOx/Ta2O5/WO3-x

In the present investigation, the electrochromic properties of a fast protonic solid state device: NiOx/Ta2O5/WO3-x prepared at room temperature (300K) is reported. The non-stoichiometric tungsten oxide thin film is prepared by reactive DC magnetron sputtering technique on ITO coated glass; the oxides of tantalum (300nm) and nickel (100nm) are prepared by electron beam evaporation. This proton device has a coloration efficiency of 82.4cm2/C and coloration and bleaching time of 6 and 5s, respectively, and a transmittance variation of 60%. The work function of WO3-x thin films by Kelvin probe in uncolored and colored states are 4.73 and 4.30eV, respectively.