Kinetics of electrochromic effect in amorphous tungsten trioxide films

Reversible coloration occurs in tungsten trioxide (WO3) films when double injection of electrons and ions is provided in its volume. Experiments were performed in electrochemical cell with liquid electrolyte, where protons were used for injection in amorphous WO3 films. Kinetics of electrochromic coloration process was studied in spectral range of 300 nm to 1200 nm. Dependence of optical density on injected charge was found to be different in various spectral regions for coloring and bleaching. Infrared vibrational spectra of electro-chemically colored crystalline and amorphous WO3 were obtained. Electronic structure features of amorphous WO3 related to electorchromism are discussed.