Theoretical study of transport properties of B40 and its endohedral borospherenes in single-molecule junctions

TL;DR

This theoretical study shows that B40 borospherenes can form highly conductive single-molecule junctions with improved charge injection and tunable conductance through doping, making them promising for molecular electronics.

Contribution

It is the first detailed theoretical analysis demonstrating the transport properties of B40 and its endohedral borospherenes in single-molecule junctions, highlighting their potential advantages over C60.

Findings

B40-based junctions have conductance comparable to C60.

Doping with Ca, Sr, or Y increases conductance significantly.

Charge injection efficiency is improved with more atoms contacting the electrode.

Abstract

C60 fullerene has been studied extensively, as it is considered to be a good candidate for building single-molecule junctions. Here, we theoretically demonstrate that the conductance of single-molecule junctions based on a newly discovered molecule, borospherene (B40), is comparable to that for the C60-based junction with its more delocalized {\pi} electrons. The charge injection efficiency in the B40-based junction is improved, as up to 7 atoms in direct contact with the electrode are possible in the Au-B40-Au junction. Interestingly, a higher number of atoms in direct contact with the electrode does not result in a higher number of conduction channels because of the unique chemical bonding in the B40 molecule, without two-center two- electron bonds. The transport properties of Au-B40-Au junctions can be proved by doping. With a Ca, Sr, or Y atom encapsulated into the B40 cage, the conductance at zero bias increases significantly. Moreover, our calculations show that the lowest unoccupied molecular orbital dominates the low-bias transport, as the thermopower in these junctions is negative. Our study indicates that B40 is an attractive new platform for designing highly conductive single-molecule junctions for future molecular circuits.