Conductive PEDOT:PSS Electrodes in Electrochromic Devices

Abstract

We present new electrochemical device designs made entirely of electrically conducting polymer electrodes to reversibly switch a magenta colored poly(3,4-propylenedioxy-thiophene) (PProDOT) electrochromic polymer (ECP) film. Thin conductive PEDOT:PSS films have been incorporated as conductive transparent electrodes in solution processable absorptive/transmissive (window type) electrochromic devices making it available for high-throughput processing on a wide range of substrates. Different (in)organic acid and polar solvent post-treatments have been used to tune the conductivity of the blade coated PEDOT:PSS electrodes. We reached a conductivity up to 2000 S cm-1 on different substrates, enough to reversibly switch our ECP film between -1 V and 1 V. We will demonstrate how the structural design, construction, charge-balancing, electrode conductivity and the electrochemical properties of the PProDOT have an influence on the device performance quantified by its contrast, switching speed, bending capabilities and long-term switching stability. We combine our device design with a fundamental study of the electrochemical processes occurring at both electrodes. Using these new designs, we have developed an all-polymer solution processed electrochromic device approaching the characteristics of a device made using inorganic transparent conducting electrodes, e.g. indium tin oxide (ITO), with the added advantage of using flexible and rough substrates. Figure 1