Organic Field-Effect Transistors for Interfacial Chemistry: Monitoring Reactions on SAMs at the Solid–Liquid Interface

Chemical modification of self-assembled monolayers (SAMs) at the solid-liquid interface can effectively impart SAMs with desired functions on demand. However, appropriate methods to monitor organic reactions at the solid-liquid interface have not yet been established. Therefore, this perspective introduces an extended-gate type organic field-effect transistor (EG-OFET)-based detector to monitor chemical reactions at the interface between SAMs on the extended-gate electrode of the OFET and an aqueous solution containing reactants. The EG-OFET is operated by applying gate voltages, enabling the monitoring of organic reactions on the extended-gate electrode through changes in transistor characteristics. Leveraging its amplification ability, the EG-OFET enables the sensitive detection of slight differences in product properties accompanied by variations in the charge and/or dipole moment of the SAM caused by chemical reactions at the interface. This perspective summarizes strategies, including those combined with chemometrics and microfluidic technologies, for monitoring irreversible and reversible chemical reactions at the solid-liquid interface.