Optical Characteristics of WO 3 Electrochromic Cells under Heavy Li Ion Injection

Abstract

This paper reports on conspicuous coloration phenomena in amorphous WO3 films under heavy Li ion injection levels. After heavy coloration, blue WO3 films turn into highly reflective golden-yellow films. An Li2 WO4 mixture with glycerine is tested for the effect of residual water on coloration. It is also shown that lithium ion dissolved in glycerine is not responsible for the coloration. Optical absorption spectra and electrical conductivity during coloration are measured. Optical property measurements show that the blue WO3 film changes irreversibly and reproducibly into golden yellow films as a consequence of Li injection.