Effect of ionic conduction under dielectric barriers on PEDOT:PSS electrochemical interfaces

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been widely used for electrochemical interfaces. When the surface is covered by an inhomogeneous dielectric layer, ions are injected to the uncovered part of PEDOT:PSS and then laterally diffuse to the covered part. However, this effect has not been incorporated into the device model. Here we show the effect of lateral ionic diffusion on the transient response of electrochemical interfaces. When PEDOT:PSS is partially covered by a dielectric layer, the covered part contributes to the electrochemical admittance unlike metal electrodes. This effect also makes the transient performance of organic electrochemical transistors deviate from conventional models.