Sol–gel derived nanocrystalline CeO2–TiO2 coatings for electrochromic windows

Mixed CeO2–TiO2 coatings synthesized by sol–gel spin coating process using mixed organic–inorganic Ti(OC3H7)4 and CeCl3·7H2O precursors with different Ce/Ti mole ratios were investigated by a wide range of characterization techniques. The attempts were directed towards achieving coatings with high transparency in the visible region and good electrochemical properties. Elucidation of the structural and optical features of the films yielded information on the aspects relevant to their usage in transmissive electrochromic devices. The films have been found to exhibit properties for counter electrode in electrochromic smart windows in which they are able to retain their transparency under charge insertion, high enough for practical uses. The high optical modulation and fastest switching for WO3 film in the device configuration with the Ce/Ti (1:1) film is interpreted in terms of conducive microstructural changes induced by addition of TiO2 in an amount equivalent to CeO2.