CONSTANT PHASE-ANGLE BEHAVIOR OF SNO2/WO3 THIN-FILM ELECTRODES IN ANHYDROUS LICLO4-PROPYLENE CARBONATE ELECTROLYTE

Electrochromism in WO3 evaporated thin films can be used in many practical devices. These systems are made of tungsten trioxide vacuum evaporated onto transparent and conductive substrates, ie fluorine doped tin oxide (SnO2:F) or indium-tin oxide (ITO). In this study, impedance spectroscopy is used to characterize the bilayered electrode. A constant phase angle (CPA) behavior in the low frequency range and a pseudo-capacitive-resistive parallel electrical circuit at intermediate frequency are observed. The influence on the impedance data of the amplitude of the ac signal, the cell temperature and the electrode geometry is studied. This approach allows us to present an electrical model for these bilayered non-colored electrodes.