Flexible Organic Electrochemical Transistor Based on Conjugated Conducting Polymers

In this work, we have fabricated a side-gated organic electrochemical transistor (OECT) where the source, drain, and gate terminals are screen-printed on a flexible polyethylene terephthalate substrate through a scalable screen-printing process. The semiconducting channel material is made of polyethylene dioxythiophene: polystyrene sulfonate (PEDOT: PSS), applied via spray coating. The OECT operates by volumetric gating of the channel through a gel electrolyte containing poly sodium 4-styrene sulfonate, transitioning highly conductive PEDOT+ to PEDOT0 through de-doping, biased by a positive gate voltage. Additionally, the OECT displayed a transconductance (gm) of 62.5 µA/V, mobility (µ) of 6.6×106 cm2 / Vs, and a threshold voltage (Vth) of -0.39 V, with the ON/OFF ratio being relatively low at 33.2. The repeatability was confirmed through the fabrication of three devices that exhibited nearly identical behavior. Future work emphasizes functionalizing the electrolyte to detect biomolecules such as glucose, pH, and ion species.