A review on organic electrochemical transistors (OECTs): Materials, device physics, challenges and applications

In the last decade, with advancements in the field of material science and innovative engineering designs, organic electrochemical transistors (OECTs) have found wide range of applications spanning from smart agriculture to next-generation electronics. OECTs are a paradigm shift from the conventional solid-state semiconductor field effect transistors which had propelled integrated circuits (ICs) technology and thereby digital age. Unlike, traditional metal oxide semiconductor field effect transistors (MOSFETs) which are purely based on electronic conduction, OECTs couple the electronic and ionic conduction phenomenon in the device channel and thereby depict higher device transconductance parameter. In this review, we aim to bridge the gap in critical aspects of OECTs development which includes material selection, device operation with functionalized surfaces, charge transport mechanism, multi-variant device performance optimization and interfacing the device with real world for various applications. Further, we also delve into the non-ideal behaviour of OECTs, device parameters and their effectiveness in realizing the next generation electronics, sensors, and other non-conventional applications. Finally, we cite the various challenges and viable solutions in engineering the OECTs focusing on material selection & geometrical optimization for maximizing device performance optimization, fabrication, process and reliability. Premise will serve as guidelines for researchers and engineers in developing OECT technology from a promising device to a commercial real time application device.