Backbone Engineering\nof Indacenodithiophene-Based\nPolymers for High-Performance Vertical Organic Electrochemical Transistors\nand Efficient Glucose Sensor

Organic mixed ionic-electronic conductors (OMIECs) play\na fundamental\nrole in the performance of organic electrochemical transistors (OECTs)\nand their applications. Although several depletion mode and accumulation\nmode OMIECs have been utilized for efficient OECT-based glucose sensors,\nthere are still persistent drawbacks such as including biocompatibility,\ninstability, or high detection limits. In this work, a series of indacenodithiophene-based\npolymeric OMIECs (gIDT, gIDT–T, and gIDT–DTBT) are developed,\nwhere the influences of backbone structure on their optical bandgap,\nenergy level, electrochemical propriety, charge transfer and transistor\nperformance, are systematically investigated. By applying KPF<sub>6</sub> electrolyte and vertical device structure, gIDT–DTBT-based\nvertical OECTs (vOECTs) achieved a maximum output current of –15.63\nmA, a maximum transconductance of 39.99 mS, and stable output current\n(less than ∼2% decay) over 1000 switching cycles. In addition,\nsuch vOECTs are employed to detect glucose concentrations ranging\nfrom 0.9 to 22.5 μM. A low limit of detection (0.1 μM)\nand good selectivity are demonstrated. This study indicates that the\ncombination of regulating OMIECs’ backbone structure, selecting\nappropriate electrolytes, and implementing a vertical device structure\ncan help optimize OECT performance and its biosensor applications.