Charge and Ion Transport in Radical Polymer-based Organic Electrochemical Transistors

Radical polymers are composed of a non-conjugated macromolecular backbone with open-shell sites that are present on the side chains of each repeat unit. Previously, we have demonstrated that this macromolecular design motif alters the route by which charge is transported in solid-state electronic devices when compared with the more common conjugated polymers utilized in organic electronics. Here, we report on the application of a specific high-performance radical polymer, poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl) (PTEO), as the active layer component in an electrolyte-gated organic electrochemical transistor (OECT) device structure. Specifically, we establish the differences in charge and ion transport (i.e., mixed conduction) in these inherently glassy radical polymer systems relative to many oft-used OECT semicrystalline macromolecular materials. Moreover, we highlight the unique synergies that exist between mixed conduction that exist in non-conjugated radical polymer systems. Finally, we manipulate the degree of crosslinking within the radical polymer thin films after casting of the film (i.e., through the use of photoinitiated crosslinking) in order to demonstrate a mechanically-stable, solvent-robust OECT that achieves high device performance as well.