<title>Enhanced contrast ratios and rapid-switching color-changeable devices based on poly(3,4-propylenedioxythiophene) derivative and counterelectrode</title>

Abstract

A large contrast ratio and rapid switching electrochromic(EC) polymer device which consists of laminated two-layer structure between two electrodes was proposed. The new design which only comprises an ITO coated glass electrode, a cathodic poly(3,4-propylenedioxythiophene) derivative (PProDOT-(CH<SUB>3$</SUB><SUB>2</SUB>) EC polymer film, a solid electrolyte and an Au-based counterelectrode which replaces anodic EC polymer and ITO electrode. Carbon-based counterelectrode was prepared for comparing with Au-based counterelectrode. Lithography and sputtering were used for Au patterning on glass substrate, while screen printing was used for carbon-based counterelectrode. Covering percentage of Au is less than 20%, in order to keep the electrode high transmittance. We also prepared a solid electrolyte, such as poly(methyl metracrylate)(PMMA) based containing LiClO<SUB>4</SUB> gel electrolyte for solid state applications. A special parafilm was utilized on sealing the assembly device. Color change of high contrast ratio of transmittance (&gt;(Delta) 50% T) of the device is rapidly (0.5-1s) obtained upon applied 2.5V voltage and repeatable (10,000 times). The temperature range under which the switching is stable is wide, -40 degree(s)C ~ 100 degree(s)C. The repeatability of current of EC polymer devices while color change was estimated by electrochemistry.