|
Flat
molecules better for conducting electricity
28 August 2006
In creating single-molecule electronic devices, flatter molecules
have now been shown to conduct electricity better. That principle has
long been suspected, but to demonstrate it definitively required an
innovation to existing methods for measuring conductance in nano-scale
objects.
Columbia research scientist
Latha Venkataraman has demonstrated that in creating single-molecule
electronic devices, flatter molecules conduct electricity better. That
principle has long been suspected, but to demonstrate it definitively
required an innovation to existing methods for measuring conductance in nano-scale
objects.
The field of nanotechnology involves designing machines and devices on a
nanoscale. One of the main challenges for scientists had been in figuring
out how to test the conductance of electronic components that consist of a
single molecule. Scientists have come up with a number of techniques, but
the large fluctuations in the results produced by these techniques have made
it difficult to predict how individual molecules will behave as electronic
devices.
In her previous research, Venkataraman -- together with her colleagues
Jennifer Klare, Colin Nuckolls, Mark Hybertsen and Michael Steigerwald from
Columbia’s Nanoscale Science and Engineering Center -- came up with a
refinement of one of the prevailing methods for measuring conductance in a
molecule. She used a novel amine-gold link to attach single molecules to the
gold electrodes (published in Nano Letters in March 2006).
 Left:
Conductance vs. Conformance: The diagram above illustrates how the
conductance of the molecule (the green, yellow or red structure in the
center of each model) drops as its two benzene rings are rotated relative to
one another. On the far left the molecule is shown in its flattest form, and
has the highest conductance. Diagram courtesy of L. Venkataraman.
Venkataraman
et al. have now applied this technique to provide definitive evidence
to support a long-held belief that flatter molecules conduct electricity
better than twisted ones.
“Overall, the discovery of the amine-gold link chemistry has been a
significant breakthrough in the field of molecular electronics,” said
Venkataraman. “It has enabled detailed and systematic studies of single
molecule conductance as a function of molecular properties and we can now
design, make and test single molecule devices with innovative properties.”
The work was published in the journal Nature:
Dependence of single-molecule junction conductance on molecular conformation
Source: Columbia University |