Ionic Liquid Gated Organic Electrochemical Transistors with Broadened Bandwidth

Yizhou Zhong, Prem D. Nayak, Shofarul Wustoni, Jokubas Surgailis, Jessica Z. Parrado Agudelo, Adam Marks, Iain McCulloch, Sahika Inal

Research output: Contribution to journalReview articlepeer-review

2 Scopus citations

Abstract

The organic electrochemical transistor (OECT) is a biosignal transducer known for its high amplification but relatively slow operation. Here, we demonstrate that the use of an ionic liquid as the dielectric medium significantly improves the switching speed of a p-type enhancement-mode OECT, regardless of the gate electrode used. The OECT response time with the ionic liquid improves up to ca. 41-fold and 46-fold for the silver/silver chloride (Ag/AgCl) and gold (Au) gates, respectively, compared with devices gated with the phosphate buffered saline (PBS) solution. Notably, the transistor gain remains uncompromised, and its maximum is reached at lower voltages compared to those of PBS-gated devices with Ag/AgCl as the gate electrode. Through ultraviolet-visible spectroscopy and etching X-ray photoelectron spectroscopy characterizations, we reveal that the enhanced bandwidth is associated with the prediffused ionic liquid inside the polymer, leading to a higher doping level compared to PBS. Using the ionic liquid-gated OECTs, we successfully detect electrocardiography (ECG) signals, which exhibit a complete waveform with well-distinguished features and a stable signal baseline. By integrating nonaqueous electrolytes that enhance the device bandwidth, we unlock the potential of enhancement-mode OECTs for physiological signal acquisition and other real-time biosignal monitoring applications.

Original languageEnglish (US)
JournalACS Applied Materials and Interfaces
DOIs
StateAccepted/In press - 2023
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Materials Science

Keywords

  • electrocardiogram
  • enhancement mode
  • ionic liquid
  • organic electrochemical transistor
  • response time

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