Structural and electrochemical properties of sol-gel derived Mo:CeO2, Si:Mo:CeO2 and Si:CeO2 nanocrystalline films for electrochromic devices

Mo:CeO2, Si:CeO2 and Mo:Si:CeO2 films were made by the sol-gel dip-coating technique. XRD investigations of the analogously prepared powders revealed that particle grain size of CeO2 with the addition of Mo, Si or both decreased. FT/IR spectra of the corresponding films showed that no separate Mo-oxide phase was formed while the Si containing CeO2 films had nanocrystallites of ceria as well as amorphous silica. Electrochemical investigations (cyclic voltammetry, chronocoulometry) performed in protic (0.1M LiOH) and aprotic (1M LiClO4/propylene carbonate(PC)) electrolytes showed that additions of Mo:, Si: and Mo: Si:-to ceria increased ion storage ability. The suitability of films as optically passive counter electrodes was demonstrated by making electrochromic cells with asymmetric and symmetric configurations using a Li+ doped ionic conductor (ormolyte®) and an electrochromic tungstophosphoric acid (WPA)/TiO2 gel film.