Photoconductive Gain-Enabled Organic Electrochemical Transistor for Biosensing

Increasing ion mobility is an important requirement for advancing organic electrochemical transistors (OECTs), necessitating specialized materials and optimized structural designs. Herein, we propose a photoconductive gain-enabled OECT that increases ion mobility within the electrolyte via light-matter interactions. Using photoelectroactive material as the gate component, voltage-driven redox reactions of the probe at the gate interface induce ion migration, serving as the foundation for OECT signal transduction. Furthermore, light-driven electron-hole pair separation at the gate increases the local positive charge density, promoting ion injection into the channel and amplifying signal transduction. Under light stimulation, the OECT converts light energy into an amplified current modulation, resulting in a 2.72-fold photoconductive gain and good redox potential discriminability. This system shows strong potential for using in electrochemical biosensing. The biosensor sensitivity increases 65-fold following signal transduction by the photoconductive gain-enabled OECT. The realization of high photoconductive gain in this OECT presents a substantial opportunity for the intelligent application of this technology.