Transparent conducting CeO₂-SiO₂ thin films

A new type of transparent thin films, based on two-phase materials of CeO₂-SiO₂, was developed. The films were prepared on indium tin oxide (ITO)-coated glass via a sol-gel process. A study of cyclic voltammetry was conducted on the films, using an electrolyte of 1 M LiClO₄ in propylene carbonate. Li⁺ insertion/disinsertion took place in the film. For a 25 nm thick CeO₂-SiO₂ film with 50% silica, the capacity of the charge exchange reached 6-7 mC/cm². After 380 cycles, the charge density dropped by approx. 30%. In both Li⁺-intercalated and free states, the films were highly transparent for visible light. Such films have potential application in counter-electrodes for electrochromic smart windows and other electrochemical devices.