Increasing the electrical conductivity of electrochromic PEDOT:PSS films – A comparative study

Abstract

The present work describes the preparation and characterization of PEDOT films (different commercial screen-printing grades) mixed with intrinsically conductive materials such as graphene, graphite, silver nanowires or AZO (antimony doped zinc oxide) deposited on plastic and paper substrates using screen-printing. The final objective was to develop a material that could be used both as electrochromic material and as electrode (electrically conductive) for use in electrochromic devices, avoiding the use of an extra layer of conductive material such as a TCO, allowing the use of different substrates, shapes or sizes, because of the limitations found in TCO deposition. The resulting films were characterized in terms of electrical and optical properties, as well as electrochemical stability. Techniques such as cyclic voltammetry, UV–visible spectroscopy, scanning electron microscopy and mechanical tests were also used. Electrochromic devices (ECDs) were assembled using these PEDOT based electrodes. The performances of the resulting devices (3 layer structures) were compared with that of conventional ones (5 layer structures) through the analysis of the device color contrast over time during continuous operation conditions using a cycling program.