Electrochemical Properties of WO 3 · x ( H 2 O ) : III . Complex Plane Analysis of the Film on

Abstract

Complex plane analysis of evaporated films on coated glass substrate has been performed in propylene carbonate electrolytes as a function of frequency from 100 kHz to 100 mHz at various applied voltages. It has been confirmed that the electron injection process at the film interface, the electrochemical charge‐transfer process in the film and a diffusion‐controlled process in the bulk are important processes at high , medium , and low frequencies , respectively. The change of electrochromic activity of various films depends mainly on the charge‐transfer process in the film; the charge‐transfer impedance increases with hydroxylation of layer and, furthermore, increases drastically with hydrated crystallization.