Gate electrode processes in an electrolyte-gated transistor: Non-Faradaically versus Faradaically coupled conductivity modulation of a polyacetylene ionomer

The significance of gate electrode processes to the transfer characteristics of electrochemical transistors is demonstrated using a device based on a polyacetylene ionomer. Two regimes of operation are identified. The first involves a conventional redox process where two Faradaic processes balance: oxidative doping of the polymer to modulate conductivity is coupled to reduction at the gate electrode. The second involves a nonconventional hybrid mode of operation: doping is coupled to the charging of an ionic double layer at the gate electrode, which is a non-Faradaic process. The implications of these two regimes on the design and performance of electrochemical transistors are discussed.