Verdazyl-based Radical Polymers and their Performance in Organic Electrochemical Transistors

Organic electrochemical transistors (OECTs) have been implemented in a wide array of sensing and biomedical applications. These devices typically employ conducting polymers based on a doped conjugated polymer design motif. Our work employs non-conjugated radical polymers in these devices due to their ambient stability, scalable syntheses, tunable electronic properties, and optical transparency relative to conjugated macromolecules. Here, we describe the design, synthesis, optoelectronic, and electrochemical properties of a next-generation radical polymer. Specifically, we have evaluated the performance of polyoxo-3-(2-mercapto ethyl)-1,4-dihydro-1,2,4,5-tetrazin-6-one (PVEO), which is an open-shell macromolecule whose backbone is based upon an ethylene oxide repeat unit structure. This macromolecular backbone motif imparts a low glass transition temperature to the radical polymer, which we have previously established is critical for high-performance electronic properties to be had. Spin characterization of PVEO revealed a Lorentzian-shaped curve, indicating a high degree of radical-radical coupling. This further implies that the presence of a high density of redox-active sites would potentially provide sufficient conductivity required for the operation of the OECTs.