Large Transconductance of Electrochemical Transistors Based on Fluorinated Donor-Acceptor Conjugated Polymers

Abstract

Organic electrochemical transistors (OECTs) have enor-mous potential for use in biosignal amplifiers, analyte sensors, and neuromorphic electronics owing to their exceptionally large trans-conductance. However, it is challenging to simultaneously achieve high charge carrier mobility and volumetric capacitance, the two most important figures of merit in OECTs. Herein, a method of achieving high-performance OECT with donor-acceptor conjugated copolymers by introducing fluorine units is proposed. A series of cyclopentadithiophene- benzothiadiazole (CDT-BT) copolymers for use in high-performance OECTs with enhanced charge carrier mobility (from 0.65 to 1.73 cm2 center dot V-1 center dot s-1) and extended volumetric capacitance (from 44.8 to 57.6 F center dot cm-3) by fluorine substitution is achieved. The increase in the volumetric capacitance of the fluorinated polymers is attributed to either an increase in the volume at which ions can enter the film or a decrease in the effective distance between the ions and polymer backbones. The fluorine substitution increases the backbone planarity of the CDT-BT copolymers, enabling more efficient charge carrier transport. The fluorination strategy of this work suggests the more versatile use of conjugated polymers for high-performance OECTs.