On the Current Saturation Observed in Electrochemical Polymer Transistors

Electrochemical transistors based on conjugated polymers are proposed as a path to printed electronics on paper. The electrochemical doping/dedoping of conjugated polymers clearly plays a role in the current vs potential characteristics of these devices, however, the mechanism of current saturation (often referred to as pinch-off) is not clearly understood, and the relationship between electrochemical devices and field-effect transistors is unclear. This paper offers a semiempirical model of the steady-state behavior of electrochemical transistors and compares this model with experimental observations of potential and electrochromic measurements within a device to illustrate the science behind the functionality observed.