Conductance Properties of Carbon-Based Molecular Junctions

TL;DR

This paper investigates the conductance properties of carbon-based molecular junctions using first-principle methods, revealing how electronic structure influences electron transport and contact conductance in oligomer nanojunctions.

Contribution

It provides a detailed analysis of off-resonant conductance spectra in oligomer nanojunctions, linking electronic structure to transport properties with first-principle calculations.

Findings

Inverse decay length is determined by the complex-band structure.

Contact conductance depends on local density of states and interfacial contact.

Conductance behavior is consistent across various energies within the conduction gap.

Abstract

We present a comprehensive study of the properties of the off-resonant conductance spectrum in oligomer nanojunctions between graphitic electrodes. By employing first-principle-based methods and the Landauer approach of quantum transport, we identify how the electronic structure of the molecular junction components is reflected in electron transport across such systems. For virtually all energies within the conduction gap of the corresponding idealised polymer chain, we show that: a) the inverse decay length of the tunnelling conductance is intrinsically defined by the complex-band structure of the molecular wire despite ultrashort oligomer lengths of few monomer units, and b) the contact conductance crucially depends on both the local density of states on the metal side and the realised interfacial contact.