Inkjet Printing of Functional Ionogels for Flexible and Transparent Conductive Electrode Materials

Printed electronics represent an emerging area of research that promises large markets due to the ability to bypass traditional expensive and inflexible silicon-based electronics to fabricate a variety of devices on flexible substrates using high-throughput printing approaches.One of the major targets in printed electronics is reducing the overall process temperature. In roll-2-roll manufacturing common polymer foils are used that often have a relative low glass transition temperature (Tg), usually below 150 °C. In order to produce conductive features on these polymer foils the often used approach of printing inorganic nanoparticles and subsequent sintering by heating cannot be used, since high temperatures are necessary, although selective sintering techniques like microwave or plasma exposure can be used.We present here a simple, practical approach to prepare ionic liquid gels that show conductivity in the semi-conductive region without the necessity of heating or sintering. Furthermore, these ionogel films are flexible and show optical transparency greater than 94% from near-UV to near-IR.