Ionic liquid crystal elastomers-based flexible organic electrochemical transistors: Effect of director alignment of the solid electrolyte

Organic electrochemical transistors (OECTs) have attracted great attention since their discovery in 1984 due to their flexibility and biocompatibility. Although an intense focus has been put on the design of new organic semiconductors, fewer efforts are directed toward the development of optimized electrolytes. However, the electrolyte is an integral part of OECTs and strongly influences the transient responses of these devices. Also, best performing OECTs currently use liquid electrolytes, but there is a growing need for solid electrolytes, as they can be easily integrated into wearable devices. In this paper, we demonstrate that ionic liquid crystal elastomers (iLCEs) can be used as solid electrolytes of flexible, substrate-free organic electrochemical transistors. We introduce the alignment of the director of the liquid crystal elastomers as a new parameter to tune and improve both steady state and transient responses. The normalized maximum transconductance gm/w of the most sensitive iLCE was found to be the highest (7 Sm−1) among all solid state-based OECTs.