Model for the bleaching of WO3 electrochromic films by an electric field

Measurements have been made of the current flow in amorphous WO3 films containing electrons and mobile cations. In a configuration in which electrons are extracted at one contact and cations at the other, the current decays as t−3/4 over many decades of time. By using space-charge current flow ideas, we develop a theory that gives the correct time dependence and magnitude of the current for this double-extraction phenomenon.