Highly Sensitive and Selective Liquid-Phase OFET Sensors Based on Crosslinked Conjugated Polymers

Abstract

Sensors based on organic field-effect transistor (OFET) platform have attracted great interest due to their use as light-weight, low-cost, flexible electronics. Various OFET-based sensors have been demonstrated for sensing a various types of analytes including chemicals, biological species, light, and pressure. However, OFET-based sensors for detecting liquid-phase analytes have not been reported because of the poor resistance of the organic semiconductors in common organic solvents. From this critical drawback, OFET-based sensors have only frequently been demonstrated with vapor- or aqueous-phase analytes. Herein, we demonstrate highly sensitive, selective, solvent-resistant OFET-based sensors using crosslinkable organic semiconductor, P3HT-azide copolymer. The chemically cross-linked P3HT-azide copolymers have been introduced to enhance the chemical resistance of semiconducting layer to common organic solvents. Moreover, calixarene derivatives have been adopted to increase selectivity of the OFET-based sensors. Various liquid-phase organic solvents as well as pH solutions have been tested successfully and reliable sensing responses have been obtained. The computational studies at the atomistic level have also been conducted to analyze the interactions between the analytes and sensors, supporting the experimental results. Our findings demonstrate a novel methodology for the fabrication of high-performance organic sensors and substantially extend the practical applications of OFET-based sensors.