Current saturation and Coulomb interactions in organic single-crystal transistors

TL;DR

This study investigates high-density charge transport in rubrene organic FETs, revealing current saturation and increased activation energy, explained by a microscopic model of interacting Frohlich polarons, advancing understanding of organic electronic transport.

Contribution

It introduces a microscopic model for interacting Frohlich polarons that explains current saturation and activation energy increase in high-density organic FETs.

Findings

Current saturation observed at high carrier densities.

Activation energy for transport increases with carrier density.

The Frohlich polaron model accurately explains experimental results.

Abstract

Electronic transport through rubrene single-crystal field effect transistors (FETs) is investigated experimentally in the high carrier density regime (n ~ 0.1 carrier/molecule). In this regime, we find that the current does not increase linearly with the density of charge carriers, and tends to saturate. At the same time, the activation energy for transport unexpectedly increases with increasing n. We perform a theoretical analysis in terms of a well-defined microscopic model for interacting Frohlich polarons, that quantitatively accounts for our experimental observations. This work is particularly significant for our understanding of electronic transport through organic FETs.