From EGOFET to OECT: Operational Control Engineered via the Electrolyte

Abstract Electrolyte-gated transistors (EGTs) are promising platforms for chemical/biological sensing and neuromorphic computing. A key research challenge lies in the selection of appropriate semiconductor and electrolyte materials to achieve efficient, stable, and reproducible devices. This work uses honey, a natural, antimicrobial, and non-volatile material, as the versatile electrolyte in EGTs that was anchored to a paper matrix for easier handling, reducing the reservoir construction step. We fabricated honey-gated transistors (HGTs) using a P3HT (poly(3-hexylthiophene-2,5diyl)) semiconductor and tested two electrolyte configurations: pristine honey and honey mixed with lithium perchlorate (LiClO4). These configurations led to distinct EGT operating modes. With pristine honey, the device operated as an electrolyte-gated organic field-effect transistor (EGOFET), governed by a field-effect mechanism. The addition of LiClO4 shifts the device’s operation mode to that of an organic electrochemical transistor (OECT), where ionic doping modulates the channel conductivity. Key electrical parameters such as threshold voltage, transconductance, and on/off current ratio reflected this transition. Transient response measurements confirmed faster operation in EGOFET mode. Electrochemically, pristine honey exhibited excellent stability, with a wide electrochemical window (∼ 4V) in cyclic voltammetry. Impedance spectroscopy measurements show that incorporating LiClO4 to honey doubles the gate capacitance compared to the pristine honey device. These results demonstrate honey’s versatility as an electrolyte, enabling tunable EGT operation with a single semiconductor and highlighting a key design strategy for electrolyte engineering. This approach holds significant potential for sensing and neuromorphic applications.