Composite Effect on Organic-type Electrochromic Display Device by Conductive Powder

Abstract

An ECD device using composite films consisting of viologen polymer complex (polyion-complex of polymerized viologen and polystyrene-sulfonic acid) and conductive powder (SnO₂/TiO₂) has been obtained with excellent charactristics. The porous structure of composite films enables electrolyte to permeate into the film easily to give more effective electrochemical reaction, and surface of the conductive powder becomes working electrodes.
Dispersed states of viologen polymer on the consuctive powder can be evaluated from the v-Ip relationships of cyclic-voltammograms.
The increase in thickness of the composite film changes only scarcely it's electrochemical characteristics which are similar to the thin-film characteristics. On the other hand, the increase in polymer content of the composite give the thick-film characteristics of electrochemical reaction.
As composite films with smaller viologen polymer content gives faster response time but smaller contrast ratio to the device, there is an optimum polymer content for the composite.