On the interface polaron formation in organic field-effect transistors

TL;DR

This paper models how charge carriers in organic FETs interact with vibrations and polar dielectrics, revealing conditions for polaron formation that affect device behavior.

Contribution

It introduces a model that captures the combined effects of bulk vibrational coupling and interface polarization on polaron formation in organic FETs.

Findings

Polaronic states can form at lower coupling strengths due to combined interactions.

Interface effects significantly influence charge carrier localization.

Polaron self-trapping may occur without large interface interactions.

Abstract

A model describing the low density carrier state in an organic single crystal FET with high-$\kappa$ gate dielectrics is studied. The interplay between charge carrier coupling with inter-molecular vibrations in the bulk of the organic material and the long-range interaction induced at the interface with a polar dielectric is investigated. This interplay is responsible for the stabilization of a polaronic state with an internal structure extending on few lattice sites, at much lower coupling strengths than expected from the polar interaction alone. This effect could give rise to polaron self-trapping in high-$\kappa$ organic FET's without invoking unphysically large values of the carrier interface interaction.