Solid-State Organic Electrolyte-Gated Transistors Based on Doping-Controlled Polymer Composites with a Confined Two-Dimensional Channel in Dry Conditions

Donguk Kim; Hong Jang; Seungjin Lee; Bumjoon J Kim; Felix Sunjoo Kim

doi:10.1021/acsami.0c19006

Solid-State Organic Electrolyte-Gated Transistors Based on Doping-Controlled Polymer Composites with a Confined Two-Dimensional Channel in Dry Conditions

ACS Appl Mater Interfaces. 2021 Jan 13;13(1):1065-1075. doi: 10.1021/acsami.0c19006. Epub 2020 Dec 22.

Authors

Donguk Kim¹, Hong Jang², Seungjin Lee¹, Bumjoon J Kim¹, Felix Sunjoo Kim²

Affiliations

¹ Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
² School of Chemical Engineering and Materials Science, Chung-Ang University (CAU), Seoul 06974, Republic of Korea.

PMID: 33351584
DOI: 10.1021/acsami.0c19006

Abstract

We report comprehensive and comparative studies on chemical and electrochemical controls of doping characteristics of various poly(3,4-ethylenedioxythiophene) (PEDOT) composites complexed with sulfonates. Chemical treatment of PEDOT composites was conducted with a dedoping agent, tetrakis(dimethylamino)ethylene (TDAE), resulting in the changes in conformation and bulk charge-carrier density. Electrochemical control of doping states was done with a solid-state ionogel based on an ionic liquid dispersed in a polymer matrix. With this approach, we can fabricate solid-state organic electrolyte-gated transistors (OEGTs) with a large current modulation, a high mobility of holes, and a low driving voltage. Our OEGTs are operational in a dry environment and, surprisingly, form the two-dimensional channel of the interfacial charge carriers modulating the conductance under gate bias, unlike conventional liquid-based OEGTs. The charge-carrier mobility and the on-to-off current ratio reach up to ∼7 cm² V^-1 s^-1 and over 10⁴, respectively, from the chemically dedoped PEDOT composites. The ionogel-based gating of the layer of TDAE-treated PEDOT composites induces a reversible transition between a highly doped bipolaronic state and neutral/polaronic states, as revealed by the absorption profiles under gate bias. We also demonstrate in-plane OEGTs, in which the dedoped channel and the conductive source/drain electrodes are made of a single PEDOT composite layer.

Keywords: chemical doping and dedoping; conductive channel; electrochemical device; organic electrolyte-gated transistor; poly(3,4-ethylenedioxythiophene) composite; tetrakis(dimethylamino)ethylene.