Simple Interface Modification of Electroactive Polymer Film Electrodes

Understanding the role of interface properties is crucial in the search for alternative design strategies to optimize the efficiency, performance, and lifetime of both solid-state and redox active organic semiconductor devices. Recent advances have focused on controlling and tailoring interfacial effects on the morphology and molecular structure of the active film in multilayer devices triggering new developments in the area of interface engineering. Here, we demonstrate that an inorganic electrode/organic semiconductor interface modification using PEDOT:PSS as an interfacial material influences the charge and ion transport, capacitive, morphological, and color switching properties of a solution processed purple-to-clear switching electrochromic PProDOT-(CH₂OEtHx)₂ polymer film. We find that the barrier to charge transport from electrode to active material is lowered when adding this PEDOT:PSS film, allowing us to present a fully roll-to-roll compatible, simple, and versatile battery-type electrochromic device (ECD) design without the need for oxidizing the charge storage film, in combination with improved processing reproducibility. In addition to producing ECDs with minimal color differences compared to devices prepared in the more traditional and complicated manner, this new ECD design strategy provides competitive performance showing a consistent optical contrast of 50-55% and switching times of 2-4 s.