Ion exchange derived precursor materials for deposition of WO3 electrochromic films:: Spectroscopic investigations

The ion exchange route was first successfully used by Livage et al. for depositing WO3 films exhibiting reversible electrochromic effect. We report in this paper the preparation of a solid precursor material by chemically modifying this route. The short lived ion exchange derived sol on addition of H2O2 and acetic acid on further processing, yields a solid precursor material with (1) unusually enhanced stability and (2) easy solvation in alcohol. UV and infrared spectroscopic investigations give strong evidence for these two properties as manifestations of the lower degree of polymerization and coordination of the acetate ion as a chelating ligand with the tungsten atom.