Journal of the Electrochemical Society, Vol.141, No.7, 1758-1762, 1994
Electrochromism of Electrodeposited Tungsten Trioxide Films .1. Electrochemical Characterization
Electrodeposited tungsten trioxide films show fast electrochromic response both in aqueous and in nonaqueous solutions. The values of x in the tungsten bronzes, MxWO3, were determined by using a chronopotentiometric technique combined with UV/Vis spectroscopic analysis. The effect of double-layer charging was discussed. A finite diffusion control model was used to analyze the insertion behavior of M+ ions into the films. The apparent diffusion coefficient of Li+ through the electrodeposited WO3 film is about two orders of magnitude higher than that of vacuum-evaporated WO3 films, indicating that electrodeposited films are more suitable for use as display devices than vacuum-evaporated films. The higher porosity of the electrodeposited WO3 films may be a main reason for the fast electrochromic response.