Mixed ion-electron transport in organic electrochemical transistors

Organic electrochemical transistors (OECTs) have shown great promise in a variety of applications ranging from digital logic circuits to biosensors and artificial synapses for neuromorphic computing. The working mechanism of OECTs relies on the mixed transport of ionic and electronic charge carriers, extending throughout the bulk of the organic channel. This attribute renders OECTs fundamentally different from conventional field effect transistors and endows them with unique features, including large gate-to-channel capacitance, low operating voltage, and high transconductance. Owing to the complexity of the mixed ion-electron coupling and transport processes, the OECT device physics is sophisticated and yet to be fully unraveled. Here, we give an account of the one- and two-dimensional drift-diffusion models that have been developed to describe the mixed transport of ions and electrons by finite-element methods and identify key device parameters to be tuned for the next developments in the field.