Theoretical study of the charge transport through C60-based single-molecule junctions

TL;DR

This theoretical study investigates charge transport in C60-based single-molecule junctions, revealing high conductance, negative thermopower dominated by LUMO, and the impact of C60 as an anchoring group on conductance sensitivity.

Contribution

The paper provides a detailed theoretical analysis of conductance and thermopower in C60 junctions and compares C60 anchors with traditional groups, highlighting their effects on transport properties.

Findings

Gold-C60-gold junctions can be highly conductive.

Thermopower is negative and can reach tens of micro-V/K.

C60 anchors influence conductance sensitivity and are affected by binding geometry.

Abstract

We present a theoretical study of the conductance and thermopower of single-molecule junctions based on C60 and C60-terminated molecules. We first analyze the transport properties of gold-C60-gold junctions and show that these junctions can be highly conductive (with conductances above 0.1G0, where G0 is the quantum of conductance). Moreover, we find that the thermopower in these junctions is negative due to the fact that the LUMO dominates the charge transport, and its magnitude can reach several tens of micro-V/K, depending on the contact geometry. On the other hand, we study the suitability of C60 as an anchoring group in single-molecule junctions. For this purpose, we analyze the transport through several dumbbell derivatives using C60 as anchors, and we compare the results with those obtained with thiol and amine groups. Our results show that the conductance of C60-terminated molecules is rather sensitive to the binding geometry. Moreover, the conductance of the molecules is typically reduced by the presence of the C60 anchors, which in turn makes the junctions more sensitive to the functionalization of the molecular core with appropriate side groups.