Electrochromism in WO3 and WO3-Pt doped nanophasic thin films deposited by MOCVD on gold substrates

Nanophasic polycristalline yellow tungsten trioxide thin films, both pure and platinum doped, have been deposited by MOCVD at 500°C in flux of oxygen mixed with water vapor on gold substrates, using W(CO)6 and Pt(II)acetylacetonate as tungsten and platinum doping sources respectively. The films were analysed by X-ray diffraction (XRD) highlighting a polycrystalline structure without preferential orientation and by scanning electron microscopy (sem) showing for Pt doped samples the formation of bigger grains than those obtained in the undoped deposits. The electrochromic behaviour of all the samples was studied by cyclic voltammetry. while the pure WO3 films present a good electrochromic coloration-decoloration (yellow to blue ) process for severtal cycles, those which are platinum doped are characterized by a not reversible color chenge process with an increased stability of the blue coloration.