Tuning Organic Electrochemical Transistor (OECT) Transconductance toward Zero Gate Voltage in the Faradaic Mode

Songyan Yu, Erin L. Ratcliff

Research output: Contribution to journalArticlepeer-review

Abstract

In this work, we investigate material design criteria for low-powered/self-powered and efficient organic electrochemical transistors (OECTs) to be operated in the faradaic mode (detection at the gate electrode occurs via electron transfer events). To rationalize device design principles, we adopt a Marcus-Gerischer perspective for electrochemical processes at both the gate and channel interfaces. This perspective considers density of states (DOS) for the semiconductor channel, the gate electrode, and the electrolyte. We complement our approach with energy band offsets of relevant electrochemical potentials that can be independently measured from transistor geometry using conventional electrochemical methods as well as an approach to measure electrolyte potential in an operating OECT. By systematically changing the relative redox property offsets between the redox-active electrolyte and semiconducting polymer channel, we demonstrate a first-order design principle that necessary gate voltage is minimized by good DOS overlap of the two redox processes at the gate and channel. Specifically, for p-type turn-on OECTs, the voltage-dependent, electrochemically active semiconductor DOS should overlap with the oxidant form of the electrolyte to minimize the onset voltage for transconductance. A special case where the electrolyte can be used to spontaneously dope the polymer via charge transfer is also considered. Collectively, our results provide material design pathways toward the development of simple, robust, power-saving, and high-throughput OECT biosensors.

Original languageEnglish (US)
Pages (from-to)50176-50186
Number of pages11
JournalACS Applied Materials and Interfaces
Volume13
Issue number42
DOIs
StatePublished - Oct 27 2021

Keywords

  • Marcus-Gerischer
  • density of states (DOS)
  • electron transfer
  • faradaic mode
  • organic electrochemical transistor (OECT)
  • organic semiconducting polymer
  • sensing

ASJC Scopus subject areas

  • Materials Science(all)

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