An unbalanced load resistor for ideal logic levels and maximum gain in organic electrochemical transistor-based unipolar inverters

Abstract

Organic electrochemical transistors (OECTs) have garnered significant attention in recent years due to their unique ion-to-electron transduction capability. These devices operate by inducing ionic swelling in the channel, leading to doping/dedoping processes that result in high current density with low operating voltages. Among numerous OECT-based applications, unipolar inverters have gained attention in the last few years due to their useful application in logic structures, mainly as building blocks in neuromorphic computing. Although OECT-based inverters have shown promising gain and voltage-transfer characteristics, guidelines for circuit designs to optimize their performance are missing. Here, we explore the influence of circuit design, operating voltages and load resistance on the output logic levels and maximum gain for two well-known organic semiconductors: PEDOT:PSS and P3HT. Our results demonstrate a non-intuitive relationship between the inverter and OECT voltages caused by the initial channel conductivity. Additionally, the influence of the load resistance on the logic levels and maximum gain is examined, revealing a trade-off between achieving ideal logic levels and maximizing gain. These findings provide an overview of critical design parameters and their impact on the inverter operation, which can guide the engineering of OECT-based complex circuits, such as artificial neurons.