Fermi level alignment in single molecule junctions and its dependence on interface structure

TL;DR

This paper investigates how the Fermi level alignment in single molecule junctions depends on interface structure, using density functional theory to analyze different molecules and bonding configurations, revealing significant effects on electron transport.

Contribution

It provides a detailed analysis of Fermi level alignment dependence on interface structure and bonding, linking quantum-chemical concepts to molecular electronics.

Findings

Fermi level alignment varies significantly with interface structure.

Bonding configuration influences electron transparency.

Density functional theory effectively models these effects.

Abstract

The alignment of the Fermi level of a metal electrode within the gap of the highest occupied and lowest unoccupied orbital of a molecule is a key quantity in molecular electronics. Depending on the type of molecule and the interface structure of the junction, it can vary the electron transparency of a gold/molecule/gold junction by at least one order of magnitude. In this article we will discuss how Fermi level alignment is related to surface structure and bonding configuration on the basis of density functional theory calculations for bipyridine and biphenyl dithiolate between gold leads. We will also relate our findings to quantum-chemical concepts such as electronegativity.