Novel Material for n-Type Organic Electrochemical Transistors

Organic electrochemical transistors (OECTs) are attractive for applications in chemical and biological sensors, neuromorphic computing, and reconfigurable electronics. An OECT consists of three electrodes (source, drain, and gate), an organic mixed ionic-electronic conductor (OMIEC) channel connecting the source and the drain, and an electrolyte between the gate and the channel. The development of OECTs has been strongly linked to advances in OMIECs. The OECT active material needs to accommodate ion transport, electronic transport, ion-electronic coupling, and air stability. For these reasons, early development of OMIECs has focused mostly on p-type polymer materials because of their superior air-stability and processability. As for n-type OECT polymer active materials, the bottle-neck is usually air-stability because n-type polymers with lowest unoccupied molecular orbital (LUMO) higher than -4.0 eV react with oxygen at ambient condition. In this work, we report an approach to make n-type OECTs from a solution-processable perylene diimide-based material. Our model material shows good n-type electronic transport, ionic transport, ion-electronic coupling, and air-stability. Via device engineering, we achieve n-type OECTs with high transconductance (49 mS) and good stability (stable after hundred-cycle weekly operation across five weeks stored in ambient air). We demonstrate the use of n-type perylene diimide-based OECTs in glucose sensors.