The Drift Diffusion Simulation of Coupled Ionic -Electronic Devices

Abstract

This thesis creates a numerical simulation scheme for a coupled ionic electronic device and uses it to simulate a memristor based on an organic conductor called poly(3,4 ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS). The modeled memristor consists of a thin PEDOT:PSS strip with a metal contact on both sides and a drop of an electrolyte solution with lithium and perchlorate ions. The conductivity of the memristor changes when the lithium ions in the electrolyte dedopes the PEDOT:PSS by bonding with PSS polymers. A numerical drift diffusion and a Poisson solver was implemented with special features to model the physical properties of the memristor. The developed simulation algorithm was tested using analytical solutions to the drift diffusion equations and Poisson's equation. 1-D and 2-D simulations were able to capture the essential physical effects. The comparison of 2-D simulations and the experimentalresults showed that proposed model worked as expected and produced results that were similar to an actual memristor. The work presented in this thesis showed promising results for the simulation of a memristor which can be improved in the future by additional modeling of the charge transport mechanisms.

Ionically-Coupled Non-Linear Variable Resistors for Neuromorphic Applications

“…15: I-V curves measured across a non-linear resistor device with varying frequency and a 3 V amplitude[26].…”