Side gate vertical OECTs for integrated complementary circuits

Abstract

Due to their unique mixed ionic-electronic working mechanism and good biocompatibility, organic electrochemical transistors (OECTs) show great potential for bioelectronics and neuromorphic electronics. Compared with the widely adopted floating gate setup, side gate OECTs, with well-defined device geometry and simpler fabrication and testing procedures, which may unleash the potential of OECTs for further integration and commercialization, are still under development. Here, the gate size (SG) and gatechannel distance (DGC) of side gates in vertical OECTs are precisely modulated by combining high-resolution printed silver gates and photo-patternable transistor channels. It is demonstrated that the performances of Homo-gDPP-based vOECTs show distinct variation when SG and DGC vary from 200 to 1600 μm² and from 500 to 15 μm, respectively, for a channel area of only 30 × 30 μm². Champion on current, peak transconductance, on/off current ratio of 13.83 ± 0.54 mA, 87.56 ± 2.76 mS, and (5.21 ± 0.27) × 10⁸, are obtained with SG of 1600 μm² and DGC of 15 μm, which are among the highest of reported side gate OECTs. Moreover, high-density complementary circuits are integrated in combination with channel size and SG control, revealing the fastest switching speed (< 9 ms) among reported side gate OECT circuits based on solid electrolytes. This work provides the strategy for the optimal design and performance enhancement of OECTs and demonstrates ways for the miniaturization and integration of next-generation electronics based on OECTs.