Researchers in Korea say they found a way to potentially accelerate the development of high-performance organic electrochemical transistor devices with tunable transient responses.
Organic mixed ionic-electronic conductors (OMIECs) offer potential bioelectric applications. Researchers at the Gwangju Institute of Science and Technology (GIST) used the transistors as platforms for testing the molecular orientation and ion injection directionality-dependent transient properties of OMIECs.
Potential applications for OMIECs include computing and bio-fuel cells in addition to bioelectronics. The researchers say that, to ensure a wider acceptance of these materials, there remains a need to diversify their properties and develop techniques for application-specific OMIEC tailoring. They cite a “severe” lack of research on the molecular orientation-dependent transient behaviors of such conductors.
The team at GIST, consisting of researchers from both Korea and the UK, set out to bridge the gap in understanding there. Professor Myung-Han Yoon from the GIST School of Materials Science and Engineering led the researchers. They explored the transient behaviors of OMIECs governed by variations in molecular orientation with the help of an organic electrochemical transistor (OECT).
“OECTs are known to mimic the computing mechanisms of neurons and synapses in spiking neural networks (SNNs) and are thus considered promising,” said Yoon. “To aid the growing interest in exploring the dynamic behaviors of OECTs at the frequency domain, we focused on an aspect that is often overlooked. We decided to investigate the correlation between backbone planarity-dependent molecular orientation and transient OECT characteristics.”
First, they synthesized two new 1,4-dithienylphenylene (DTP)-based OMEICs, DTP-2T and DTP-P, with co-monomer units, 2,2’-bithiophene and phenylene, respectively. According to GIST, the polymers comprised the same ionic and electronic properties. However, by manipulating the polymer backbone planarity, the researchers controlled the dominant molecular orientation of the mixed conductor system.
This polymer then successfully helped to fabricate OECT devices. The team found that the polymers showed similar electrochemical properties despite having different molecular orientations. They then changed the ion injection direction when observing a certain current/voltage during the analysis. In the analysis, the researchers saw that ion injection relative to the molecular orientation affected the length of the ion drift pathway. This, in turn, resulted in peculiar transient responses in OECT devices.
The team believes it could use its research to facilitate the design and development of advanced organic mixed conductor materials for biomolecular and biosignal sensors.
“OECT-based SNN architectures are anticipated to replace current computing systems in the future by increasing computation speed and reducing energy consumption,” Yoon said. “Our findings are expected to facilitate the realization of SNN-based computing systems soon.”
