Steady‐State and Transient Behavior of Organic Electrochemical Transistors

Abstract

In recent years, organic electrochemical transistors (OECTs) have emerged as attractive devices for a variety of applications, particularly in the area of sensing. While the electrical characteristics of OECTs are analogous to those of conventional organic field effect transistors, appropriate models for OECTs have not yet been developed. In particular, little is known about the transient characteristics of OECTs, which are determined by a complex interplay between ionic and electronic motion. In this paper a simple model is presented that reproduces the steady‐state and transient response of OECTs by considering these devices in terms of an ionic and an electronic circuit. A simple analytical expression is derived that can be used to fit steady‐state OECT characteristics. For the transient regime, comparison with experimental data allowed an estimation of the hole mobility in poly(3,4‐ethylenedioxythiophene) doped with poly(styrene sulfonate). This work paves the way for rational optimization of OECTs.

High transconductance organic electrochemical transistors

“…The drain current decreases with gate voltage, consistent with operation in the depletion regime. This behaviour is in agreement with our current understanding of the operation mechanism of OECTs16: when a positive bias is applied at the gate, cations from the electrolyte enter the PEDOT:PSS film and compensate the pendant sulphonate anions on the PSS. This leads to a decrease of the hole density in the PEDOT, as holes extracted at the drain are not re-injected at the source.…”

Antibody-Coated Wearable Organic Electrochemical Transistors for Cortisol Detection in Human Sweat

“…The volumetric capacitance C v of the PEDOT:PSS material was also extracted from the impedance spectroscopy measurements (Figure S9), and it is equal to about 24 F/cm 3 , in agreement with previously reported values . Considering that the term in eq is equivalent to , and being the conductance of the organic material, the hole mobility was estimated to be 6 cm 2 V s –1 , similar to previously reported PEDOT:PSS values . For the different channel geometries, the C dl,channel values are then 2 μF for the short channel (volume 0.072 cm 3 ), 14 μF for the medium channel (volume 0.6 cm 3 ), and 10 μF for the long channel (volume 0.4 cm 3 ).…”

Surface Functionalization with (3-Glycidyloxypropyl)trimethoxysilane (GOPS) as an Alternative to Blending for Enhancing the Aqueous Stability and Electronic Performance of PEDOT:PSS Thin Films

“…The output characteristics (Figure S3a,b) and transfer curves (Figure S3c,d) at drain voltage, V D = −0.6 V for P@GOPS and P:GOPS show that the drain current, I D , decreases with gate voltage, V G , due to the injection of cations from the electrolyte which compensates the sulfonate counterions leading to a decrease in hole density in the PEDOT. This result is consistent with the common operating mechanism of OECTs. , The transfer curve also showed that both devices exhibited a similar ON/OFF ratio of ∼70 for P@GOPS and ∼77 for P:GOPS. The figure of merit that measures the effective signal amplification of an OECT is the transconductance, defined as g m = ∂I D / ∂V G .…”