IMPEDANCE SPECTROSCOPY ANALYSIS OF WO3 THIN-FILM ELECTRODES DURING ELECTROCHROMIC COLORING-BLEACHING CYCLING

This paper deals with the variations in the electrical components (resistances, capacitances and constant phase element) of an electrochromic electrode during colouring-bleaching cycling. The complex impedance method is used to determine these parameters. Two types of electrochromic material are investigated: tungsten trioxide thin films obtained by anodic oxidation of tungsten sheet or by thermal vacuum evaporation of WO3 onto an SnO2:F electrode. An electrical model can be associated with the electrochromic electrode. The behaviours of these electrodes during cycling are compared and explained in terms of interface modification.