Berlin 2024 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 28: Poster III

CPP 28.27: Poster

Wednesday, March 20, 2024, 11:30–13:30, Poster C

Analytical drift-diffusion model for steady-state drain currents in organic electro-chemical transistors — •Andres Unigarro¹ and Florian Günther² — ¹Institut für Physik, Technische Universität Chemnitz, Germany — ²Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista, Rio Claro, Brazil

Among the different devices developed in the field of organic electronics, organic electrochemical transistors (OECTs) have emerged as potential transducers in applications that require the conversion of ion fluxes to electronic current. For the rational optimization and understanding of the fundamentals of OECTs and OECT-based applications, however, it is essential to have theoretical models capable to predict and recreate the experimental data. The existing models used to describe the OECT functions discussed during the past decade mostly originate from Ohm's law, where the ion flux from the electrolyte into the semiconducting layer takes place only due to an electrical field. But ion migration also occurs upon diffusion. In this work we present an approach to model the ion concentration profile under steady-state conditions based on drift-diffusion principles. This allows to formulate an analytical expression of the source-drain current as a function of gate and drain voltages but also of material parameters like the salt concentration. We show that this allows expressing the volumetric capacitance (a parameter that determines the figure of merit for OECTs) as a function of these material parameters. We furthermore present adjustments of experimental data and comparisons to other OECT models.

Keywords: organic electrochemical transistor; drift-diffusion model; PEDOT:PSS