Improvement of the poly-3-hexylthiophene transistor performance using small molecule contact functionalization

TL;DR

This study enhances poly-3-hexylthiophene transistors by functionalizing gold contacts with small molecules, significantly reducing contact resistance and improving device performance through tailored interface barriers.

Contribution

It introduces a novel contact functionalization method using monolayer molecules to improve organic transistor performance.

Findings

Contact resistance reduced by up to 16 times

Lower activation energies for charge injection

Enhanced on/off ratios in transistors

Abstract

We demonstrate an approach to improve poly-3-hexylthiophene field effect transistors by modifying the gold contacts with monolayer thick pentacenequinone (PQ) or naphthalene (NL). The effective contact resistance is reduced by a factor of two and sixteen for interlayers of PQ and NL, respectively. The observation is attributed to different injection barriers at the metal-organic interface caused by the functionalization and to an additional tunneling barrier enhancing the on/off ratios. This barrier yields to activation energies of 37meV (NL) and 104meV (PQ) below 190K, which are smaller than without functionalization, 117meV.