Benchmarking organic mixed conductors for transistors

Sahika Inal,Jonathan Rivnay,George G. Malliaras

doi:10.1038/s41467-017-01812-w

Abstract

Organic mixed conductors have garnered significant attention in applications from bioelectronics to energy storage/generation. Their implementation in organic transistors has led to enhanced biosensing, neuromorphic function, and specialized circuits. While a narrow class of conducting polymers continues to excel in these new applications, materials design efforts have accelerated as researchers target new functionality, processability, and improved performance/stability. Materials for organic electrochemical transistors (OECTs) require both efficient electronic transport and facile ion injection in order to sustain high capacity. In this work, we show that the product of the electronic mobility and volumetric charge storage capacity (µC*) is the materials/system figure of merit; we use this framework to benchmark and compare the steady-state OECT performance of ten previously reported materials. This product can be independently verified and decoupled to guide materials design and processing. OECTs can therefore be used as a tool for understanding and designing new organic mixed conductors.

Highlights

Organic mixed conductors have garnered significant attention in applications from bioelectronics to energy storage/generation
The ability for organic mixed conductors to support ion penetration has allowed for high performance organic electrochemical transistors (OECTs) to be developed as amplifying transducers for bioelectronic applications[15]
Gm is a direct measure of effective signal amplification of a single OECT; which, for instance, determines whether the OECT will be able to operate as a biosensor, i.e., transduce small biological signals

Summary

Introduction

Organic mixed conductors have garnered significant attention in applications from bioelectronics to energy storage/generation. Due to the motion of both electronic and ionic charges in the channel, mobility extraction cannot be, in a straight forward manner, performed via the transconductance method as applied for field effect transistors (FETs) For this reason, OECT researchers often report device transconductance, which is the slope of the ID − VG transfer curve, gm = ∂ID/∂VG (see Fig. 1b). The conducting polymer poly(3,4-ethylenedioxythiophene) complexed with poly(styrene sulfonate) (PEDOT:PSS) is among the most commonly studied materials in OECT research, and has allowed for significant device physics and modeling development It is stable in aqueous conditions, processable by a variety of methods, allows for both electronic and ionic transport, and importantly, is readily commercially available[3, 18]. These findings can be corroborated and derived[15], resulting in the following scaling of OECT transconductance: gm 1⁄4

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Results

Conclusion