Improved organic electrochemical transistors via crystallizable small molecule templating

Published

January 31, 2024

Author(s)

Lucas Flagg, Whirang Cho, Jeremiah Woodcock, Ruipeng Li, Lee Richter

Abstract

: Organic electrochemical transistors (OECTs) are of great interest as biosensors and for flexible electronics applications. Historically, processing techniques have been widely used to improve performance of polymers in organic electronics but have been underutilized in the field of OECTs. Here we study the effects of a crystallizable small molecule template for im-proving the performance of poly(3-hexylthiophene-2,5-diyl) (P3HT) based OECTs. We utilize the small molecule 1,3,5 tri-chlorobenzene (TCB) as a crystallizable solvent to induce directional crystallization during blade coating. This procedure results in an aligned, highly ordered, and moderately porous layer of semiconducting polymer. We find that compared to neat P3HT, films cast with TCB show a greater than 8x improvement in the steady state figure of merit for OECTs, µC*. Additionally, the optimum TCB loading produces anisotropic OECTs where the polymer chain aligned parallel to the current in the channel outperforms the perpendicular alignment by more than a factor of 10. We investigate the mechanism of this improvement and find that polymer alignment, polymer ordering, and film porosity all play a role in improving the device performance. Overall, these results demonstrate the importance of processing on the optimization of polymers for OECTs, and suggest a route to greatly improve the OECT performance of commercially available, hydrophobic polymers.

Citation

Chemistry of Materials

Pub Type

Journals

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Keywords

Polymer, OECT

Citation

Flagg, L. , Cho, W. , Woodcock, J. , Li, R. and Richter, L. (2024), Improved organic electrochemical transistors via crystallizable small molecule templating, Chemistry of Materials, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=956696 (Accessed December 13, 2025)