Sol-gel processed nanostructured CeO2–TiO2 thin films for electrochromic applications

Mixed oxide films based on Ce and Ti have been deposited on transparent conducting oxide coated glass substrates using the sol-gel technique. The nanostructural characteristics of the films derived from different precursor materials (cerium chloride and ceric ammonium nitrate) have been evidenced from the transmission electron microscopic analysis. Cyclic voltammetric investigations have shown that the Li ion diffusion in the films has been influenced by the size of the CeO2 nanograins and their distribution in the amorphous TiO2 matrix. Multiple step chronoamperometric studies have revealed that the higher thickness of the films obtained using cerium chloride has resulted in the same a greater capacity to intercalate the Li ions in view of the higher number of active insertion sites for the Li ion. The latter has consequently led to improved reversibility of the electrochromic device comprising the counter electrode based on cerium chloride. The slower coloration–bleaching kinetics of the primary working electrode (WO3) in the configuration comprising the ceric ammonium nitrate based counter electrode exemplifies the advantage of using cerium chloride for depositing CeO2–TiO2 thin films for electrochromic applications.