(Invited) Conducting Polymer Transistors Making Use of Activated Carbon Gate Electrodes

The characteristics of the gate electrode have significant effects on the behaviour of organic electrochemical transistors (OECTs), which are intensively investigated for applications in the booming field of organic bioelectronics. In this work, high specific surface area activated carbon (AC) was used as gate electrode material in OECTs based on the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrene sulfonate) (PSS).¹ We found that the high specific capacitance of the AC gate electrodes leads to high drain-source current modulation in OECTs.
Cyclic voltammetry studies, where PEDOT:PSS is used as the working electrode (WE) and AC is used as the reference electrode (RE) and counter electrode (CE), show that high double-layer capacitance and absence of Faradaic processes permit the development of stable OECTs where the channel potential is uniquely determined by the applied gate bias. The intrinsic quasi-reference characteristics of AC electrodes make unnecessary the presence of an additional reference electrode to monitor the OECT channel potential.
The ease of process of AC electrodes for in plane, flexible device architectures constitutes a step forward in the search of new electrode materials for OECTs to be used in iontronics, printed electronics, bio analytical sensing, and other organic bioelectronic devices.