Work

Unconventional molecule-resolved current rectification in diamondoid–fullerene hybrids

Year: 2014

Type: article

Abstract: The unimolecular rectifier is a fundamental building block of molecular electronics. Rectification in single molecules can arise from electron transfer between molecular orbitals displaying asymmetric spatial charge distributions, akin to p–n junction diodes in semiconductors. Here we report a novel all-hydrocarbon molecular rectifier consisting of a diamantane–C60 conjugate. By linking both sp3 (diamondoid) and sp2 (fullerene) carbon allotropes, this hybrid molecule opposingly pairs negative and positive electron affinities. The single-molecule conductances of self-assembled domains on Au(111), probed by low-temperature scanning tunnelling microscopy and spectroscopy, reveal a large rectifying response of the molecular constructs. This specific electronic behaviour is postulated to originate from the electrostatic repulsion of diamantane–C60 molecules due to positively charged terminal hydrogen atoms on the diamondoid interacting with the top electrode (scanning tip) at various bias voltages. Density functional theory computations scrutinize the electronic and vibrational spectroscopic fingerprints of this unique molecular structure and corroborate the unconventional rectification mechanism. Diamondoids are building blocks for nanostructured materials that can be used in molecular devices. Here, Randel et al.demonstrate an all-hydrocarbon single-molecule rectifier composed of a buckyball cage fused to a diamondoid, which outperforms either of its separate molecular constituents.

Source: Nature Communications

DOI: 10.1038/ncomms5877