Scalable Transconductance of Floating Gate Organic Electrochemical Transistor-Based Channels Connected in Parallel for High-Performance Ultraviolet Sensing

Abstract

Organic electrochemical transistors (OECTs) have emerged as promising candidates for ultraviolet (UV) detection owing to their low operating voltage, high transconductance, and excellent biocompatibility. However, susceptibility of the organic channel to UV-induced degradation, together with the inherently limited sensitivity of conventional OECT-based UV sensors, further restricts their practical application. We propose a triple-channel connected in a parallel floating-gate OECT (FGOECT) UV sensor with the second floating-gate functionalized with ZnO nanowires (ZnONWs), whose interface undergoes a transition from a polarized to a nonpolarized state under UV irradiation. The separated sensing–amplification architecture ensures operational stability, with the drain current decaying by only 1.39% within 1 h of continuous operation and retaining 93.07% retention ratio of its initial value after 1000 gate-voltage cycles. Through a simple channel connected in a parallel configuration, scalable transconductance is achieved without sacrificing the temporal response. Under UV irradiation, the triple-channel connected in the parallel configuration enhances the transconductance from 8.56 to 34.33 mS. The sensitivity of 2.617 (μA·cm2)/W for the FGOECT with triple-channel connected in parallel represented more than a 3-fold magnitude improvement compared with the sensitivity (0.783 (μA·cm2)/W) for the single-channel FGOECT. The corresponding enhancement factor (EF) of 3.34 confirms the realization of highly sensitive UV detection, establishing the channel connected in a parallel FGOECT as a robust and scalable platform for organic electrochemical UV sensing.