Passing current through touching molecules

TL;DR

This study investigates charge transfer between touching C60 molecules using cryogenic STM and first-principles calculations, revealing consistent low conductance and the importance of intermolecular links.

Contribution

It provides detailed experimental and theoretical analysis of charge transport in C60-C60 contacts, highlighting the role of intermolecular links and contact geometry.

Findings

C60-C60 contact conductance is consistently lower than single-molecule contacts.

Electrode geometry affects single-molecule conductance up to threefold.

First-principles calculations match experimental conductance and reveal intermolecular link importance.

Abstract

The charge flow from a single C60 molecule to another one has been probed. The conformation and electronic states of both molecules on the contacting electrodes have been characterized using a cryogenic scanning tunneling microscope. While the contact conductance of a single molecule between two Cu electrodes can vary up to a factor of three depending on electrode geometry, the conductance of the C60-C60 contact is consistently lower by two orders of magnitude. First-principles transport calculations reproduce the experimental results, allow a determination of the actual C60-C60 distances, and identify the essential role of the intermolecular link in bi- and trimolecular chains.