Presentazioni e Articoli Tecnici

Electrolyte-gated organic field-effect transistors differ from conventional OFETs by using an electrolyte as the gate insulating material. Due to a high permittivity of the electrolyte, EGOFETs tend to have a higher capacitance than their conventional non-electrolytic counterparts. Therefore, the operating voltage in these devices is considerably smaller than in the OFETs that makes them ideal for biosensing applications. In a p-channel EGOFET, upon negative polarization of the gate, the cations in the electrolyte are attracted toward the electrolyte–gate interface, while anions migrate to the electrolyte– semiconductor interface, resulting in the formation of electric double layer (EDL) at both interfaces.

In the present work, we report the steady state 2D simulation of the Electrolyte-gated organic field-effect transistor (EGOFET) using Nernst-Planck-Poisson equations (also known as Drift-Diffusion equations in semiconductor physics) as implemented in COMSOL Multiphysics^® 5.3a with the focus on the understanding and explanation of the transfer and output characteristics of the experimental devices. Since ions in the electrolyte do not penetrate into the organic semiconductor channel, the electrolyte-semiconductor boundary is blocking for both ions.

The transfer and output characteristics of the device were modeled successfully and are in good agreement with the experimental data. The formation of the electric double layers at both interfaces is observed and the evolution of the charge density across the channel is discussed.