Electron-phonon and electron-electron interactions in organic field effect transistors

TL;DR

This paper investigates how electron-phonon and electron-electron interactions influence the performance of organic FETs, focusing on the effects of dielectric properties and carrier interactions on mobility and polaron formation.

Contribution

It introduces a model combining electron-phonon and electron-electron interactions to explain mobility behavior and polaron formation in organic FETs with varying dielectric constants.

Findings

Mobility transitions from metallic-like to insulating with higher dielectric constants.

Small polaron formation is driven by charge-phonon interactions at the organic/dielectric interface.

Coulomb repulsion impacts carrier behavior at high concentrations.

Abstract

Recent experiments have demonstrated that the performances of organic FETs strongly depend on the dielectric properties of the gate insulator. In particular, it has been shown that the temperature dependence of the mobility evolves from a metallic-like to an insulating behavior upon increasing the dielectric constant of the gate material. This phenomenon can be explained in terms of the formation of small polarons, due to the polar interaction of the charge carriers with the phonons at the organic/dielectric interface. Building on this model, the possible consequences of the Coulomb repulsion between the carriers at high concentrations are analyzed.