Paterson Group Publication Enhances Merit Analysis in Organic Electronics Scientific Community

Lexington, KY – Merit analysis is a vital element of the scientific process, ensuring that research is based on rigorous evidence and sound methodology. It enables scientific advancement, boosts credibility, quality, and reliability for future research. It allows a research community to build a common language, common practices, and common logic.

Sometimes, however, a discovery occurs that contradicts the merit analysis technique, resulting in a sea change for a research community. One such change may have just occurred in the labs of the University of Kentucky’s Center for Applied Energy Research (UK CAER).

A new paper from Alexandra F. Paterson’s organic electronics group, The organic electrochemical transistor conundrum when reporting a mixed ionic-electronic transport figure of merit, challenges some traditional practices in organic electronics, particularly in organic mixed ionic-electronic conductors (OMIECs) and organic electrochemical transistors (OECTs). It was recently published in Nature Materials:

Conductors (materials that easily conduct electricity), and transistors (the on-off switches of those materials) are the bread-and-butter of our electronically driven world. Every phone, computer, light-switch, and vehicle have transistors. Typically, these are made of silicon, copper, iron, nickel, or other elements, some of which are rare-earth, and many of which are non-renewable resources. Paterson’s lab focuses on creating transistors utilizing organic materials and are more flexible than their rigid counterparts.

“Nowadays, we have billions of transistors in a smartphone. These transistors are so fundamental to our society—imagine how much impact we could have if we developed transistors with new, organic, more-environmentally-friendly materials with different mechanical properties, that can be used in new environments,” Paterson said.

The properties of OMIECs and OECTs are attracting significant interest in many application spaces. From wearable biosensors and body machine interfaces to neuromorphic computing, chemical sensing, healthcare, and agriculture, these materials are on the cutting edge of advanced manufacturing. The Paterson lab, supported KY NSF EPSCoR’s Track-1 project and UK CAER, have published several papers and continue to advance innovations in this field. As research progresses, costs are reduced, and efficiency improves.

One such paper, published in Advanced Science this July from the Paterson lab, explored chemical doping as an innovative approach for enhance the performance of OECTs:

However, as this paper explores, there is perhaps a conundrum with OECTs, when it comes to the µC* product. The µC* product is the OMIEC and OECT system figure of merit used to benchmark performance and guide the development of the field. Directly extracting the µC* product from OECTs is becoming a routine method in the organic bioelectronics and OMIEC communities. The Paterson lab paper shows that, in certain cases, OECTs inflate the µC* product beyond state of-the-art and can give inaccurate µC* product values. This marks the first publication on the accuracy of the µC* product, and the first time an exponential channel resistance has been reported in OECTs, with the latter finding explaining the cause of the overestimations.

“This work is important for the organic electronics community because, if this parameter is not extracted correctly, it can misguide the entire field, curtail acceleration and progression, impact publications, and lead to rejected funding applications. Misreported and incorrect figures of merit, extracted from electronic devices, take years to rectify,” Paterson said. “This publication is timely because it can raise concerns of incorrect figure of merit analysis within the field before it becomes widespread throughout the literature.”

Paterson’s team on this paper include post-doctoral scholar Maryam Shahi, graduate researchers Vianna N. Le and Paula Alarcon Espejo, with collaborators from University of Oxford, Professor Iain McCulloch, post-doctoral scholar Christina Kousseff and graduate student Maryam Alsufyani.

This research aligns with KY NSF EPSCoR’s Track-1 project, KAMPERS, which is in its fifth year of a five-year project, focusing on advancing manufacturing in Kentucky. Paterson is a new faculty hire, supported by the project starting in 2021. Her work, alongside Track-1 Co-PI John Anthony, UK CAER Associate Director Matt Weisenberger, and several others across UK, University of Louisville, and other institutions, are focused on developing compatible suites of printable insulators, conductors, and semiconductors for structurally integrated electronics, as well as fully integrating sensing, logic, and communication into those structures using 3D printing and related techniques. OECTs play a significant role in these objectives.

“Something our group is interested in is the concept of introducing novel electronic materials into traditional or existing transistor structures, because this process often results in nuanced and unexpected device characteristics,” Paterson said. “If we understand the phenomena behind these new behaviors, it not only gives a better understanding of current devices, but also leads to the discovery of new device concepts and design rules. This is a path to establishing new applications for organic electronics.”

In 2011, the National Science Board (NSB) issued a report on the National Science Foundation’s Merit Review Criteria: Review and Revisions. In addition to reaffirming the two merit review criteria, the report set forth three merit review principles, the first of which reads, “All NSF projects should be of the highest quality and have the potential to advance, if not transform, the frontiers of knowledge.”

With findings like these, the Paterson lab, along with other KY NSF EPSCoR supported researchers, are leading the way, powered by this principle, in Kentucky and beyond.