# Small signal analysis for the characterization of organic electrochemical transistors

## TL;DR

A new method using small signal analysis is introduced to accurately measure the performance of organic electrochemical transistors.

## Contribution

The paper introduces a small signal analysis method that enables precise determination of electronic mobility and other parameters in OECTs.

## Key findings

- Small signal analysis allows accurate electronic mobility measurement with a standard AC potentiostat.
- The method excludes parasitic components in both ionic and electronic conduction with low standard deviation.
- The technique is applicable to various OECT materials and operation modes.

## Abstract

A method for the characterization of organic electrochemical transistors (OECTs) based on small signal analysis is presented that allows to determine the electronic mobility as a function of continuous gate potential using a standard two-channel AC potentiostat. Vector analysis in the frequency domain allows to exclude parasitic components in both ionic and electronic conduction regardless of film thickness, thus resulting in a standard deviation as low as 4%. Besides the electronic mobility, small signal analysis of OECTs also provides information about a wide range of other parameters including the conductance, transconductance, conductivity and volumetric capacitance through a single measurement. General applicability of small signal analysis is demonstrated by characterizing devices based on n-type, p-type, and ambipolar materials operating in accumulation or depletion modes. Accurate benchmarking of organic mixed ionic-electronic conductors through small signal analysis can be anticipated to guide both materials development and the design of bioelectronic devices.

Accurate determination of the performance of organic electrochemical transistors is challenging. The authors present a method for the device characterization based on small signal analysis, enabling the determination of the electronic mobility as a function of continuous gate potential.