Photo-Patternable PEDOT:PSS for High Performance Organic Electrochemical Transistors

Organic mixed ionic-electronic conductors (OMIECs) have the unique ability to transport both ionic and electronic charges, making them the ideal choice for interaction between biology (ionic) and human technology (electronic). Applied first to sense biological environments, OMIECs are now used to develop brain-inspired circuits capable of seamlessly "communicating" with biology. However, patterning these organic materials in complex circuits is a challenge as traditional microfabrication techniques are not fully compatible. Current research is still heavily relying on a technique called peel-off, which involves the physical removal of a sacrificial layer, making it cumbersome to develop highly integrated circuits. To circumvent these fabrication limitations, a photo-patternable PEDOT:PSS is developed by blending it with a photo-sensitive interpenetrating network, allowing features down to 2 µm to be patterned using photolithography on a wide range of substrates. The process fully retains the ability of the OMIEC to transport ions and electrical charges; moreover, organic electrochemical transistors fabricated using this technique outperform the widely used chemically-cross-linked GOPS PEDOT:PSS, while having a batch-to-batch variability below 5%. Our photo-patterning process opens the door to monolithic fabrication of miniaturized and highly integrated circuits, allowing to push the limits of interaction between biology and man-made technology.