Dithiocarbamate Anchoring in Molecular Wire Junctions: A First Principles Study

TL;DR

This study uses first-principles calculations to investigate how dithiocarbamate linkers affect electron transport in molecular wire junctions, revealing enhanced conductance and rectification properties.

Contribution

It demonstrates the impact of dithiocarbamate anchoring groups on electron transport and rectification in molecular junctions using density functional theory and Green's functions.

Findings

Dithiocarbamate linkers broaden transmission resonances near the Fermi level.

Conductance of BPBC molecule is enhanced up to 25 times at 1.0 V bias.

BPC junction exhibits rectification due to asymmetric anchoring groups.

Abstract

Recent experimental realization [J. Am. Chem. Soc., 127 (2005) 7328] of various dithiocarbamate self assembly on gold surface opens the possibility for use of dithiocarbamate linkers to anchor molecular wires to gold electrodes. In this paper, we explore this hypothesis computationally. We computed the electron transport properties of 4,4'-bipyridine (BP), 4,4'-bipyridinium-1,1'-bis(carbodithioate) (BPBC), 4-(4'-pyridyl)-peridium-1-carbodithioate (BPC) molecule junctions based on the density functional theory and non-equilibrium Green's functions. We demonstrated that the stronger molecule-electrode coupling associated with the conjugated dithiocarbamate linker broadens transmission resonances near the Fermi energy. The broadening effect along with the extension of the $\pi$ conjugation from the molecule to the gold electrodes lead to enhanced electrical conductance for BPBC molecule. The conductance enhancement factor is as large as 25 at applied voltage bias 1.0 V. Rectification behavior is predicted for BPC molecular wire junction, which has the asymmetric anchoring groups.