Electrochemical Fabrication and Characterization of Organic Electrochemical Transistors Using poly(3,4-ethylenedioxythiophene) with Various Counterions

Abstract

Organic electrochemical transistors (OECTs) are promising bioelectronic devices, especially because of their ability to transport charge both ionically and electronically. Conductive polymers are typically used as the active materials of OECTs. Crosslinked, cast, and dried films of commercially available poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PE-DOT:PSS) suspensions are commonly and widely used for OECTs so far. Electrochemical polymerization of PEDOT from 3,4-ethylenedioxythiophene (EDOT) monomer can also be used to fabricate OECTs; however, this approach has not been investigated in as much detail. In particular, the role of various counterions that can be incorporated into the PEDOT films of OECTs has not been systematically studied. Here, we report the electrochemical fabrication and characterization of OECTs using PEDOT with several different counterion salts including lithium perchlorate (LiClO 4 ), sodium p-toluene sulfonate (pTS), and poly(sodium 4-styrene sulfonate) (PSS). We found that the characteristic dimensions of PEDOT films deposited on the electrodes could be precisely controlled by total charge density, with a nominal thickness of about one micron requiring a current density of about 0.6 C/cm 2 regardless of the choice of counterion. The films with the PSS counterion were relatively smooth, while PEDOT films prepared with the pTS and LiClO 4 were much rougher due to the sizes of counterions. The PEDOT films with pTS and PSS grew along the substrate surface (in-plane direction) much faster than with LiClO 4 . The maximum transconductance (g m ) of a PEDOT OECT was 46 mS with pTS as the counterion with the high on-current level (>10 mA) based on the large channel area. These results provide an effective and efficient way to fabricate OECTs with various monomers and additives as active materials in order to modify the device characteristics for further applications.

Influence of Controlled Chirality on the Crystallization of Maleimide-Functionalized 3,4-Ethylenedioxythiophene (EDOT-MA) Monomers

“…Being organic in nature, their mechanical and physical properties are significantly different than those of inorganic conducting materials. They have been investigated for use in a variety of applications such as organic electrochemical transistors, , capacitors, , photovoltaics, , electrochromic displays, bioelectronics, and chemical sensors…”

Vertical organic electrochemical transistor platforms for efficient electropolymerization of thiophene based oligomers

“…[1][2][3][4][5][6] This advancement is due in part to the development of new OECT channel materials with mixed ionic-electronic conduction, beneficial for interfacing directly with electrolyte environments. [7][8][9][10][11][12][13] The mixed conduction mechanism of the semiconducting channel material is ideal for bioelectronic applications aiming to achieve signal transduction between ionic fluctuations and electrical currents. Although the OECT materials toolbox has greatly expanded over the past years, the practical need of solution processability to enable standard deposition techniques has limited the use of promising materials requiring electropolymerization.…”

High-Performance Organic Electrochemical Transistor Based on Photo-annealed Plasmonic Gold Nanoparticle-Doped PEDOT:PSS

“…Commonly used strategies to improve electrical properties of organic semiconductors and to fabricate high-performance OECTs include side chain engineering and channel doping, among which channel doping is highly simple, convenient, and effective. Ethylene glycol (EG), , inorganic salts (such as lithium and ammonium salts), , and surfactants have been doped in channel materials of OECTs to improve the output performances due to the improved polarity, crystallinity, microstructure, and/or interface quality.…”