New electrochromic material based on the electrochemical insertion of lithium into bleached potassium hexatungstate

Abstract

It has been shown that K 0·3WO 3·15 thin films can be used as lithium-based electrochromic display materials. One of the important parameters in such applications is the chemical diffusion coefficient of the coloring species. Thus the chemical diffusion kinetics of lithium have been evaluated in thin films of this material prepared by thermal vacuum evaporation and bleached by oxidation. Measurements have been made as a function of lithium concentration using the galvanostatic transient technique. Chemical diffusion coefficients as high as 10 −10 cm 2/sec at room temperature were obtained in films prepared such that they exhibit a strong preferred orientation. Electrical cycling experiments showed no evidence of structural degradation after over 1000 deep charge/discharge cycles performed under potentiostatic conditions.