Large tunable image-charge effects in single-molecule junctions

Researchers at Leiden University and Delft determined what makes electron transport in a single molecule so difficult thanks to a new measurement technique. One of the leaders of the team comments that the expectations they have are for large surfaces, like displays where there is a great advantage to having a single layer of molecules that can be p

ut together simply and cheaply.

This study offers insight into fundamental physical behavior of individual molecules. A molecule can act as a very sensitive sensor or nanotransistor between two electrodes, but the problem with the development of this type of molecular electronics is that it is really difficult to make electrical contact with a single molecule.

Researchers were able to create a new method for measuring conductivity in a molecule which is based on the mechanically driven break junction technique developed by Prof. Jan van Ruitenbeek. The paper explains that a freely suspended bridge in a metal conductor is subjected to mechanical pressure so it bends and breaks. Then, the molecule attaches itself to the two clean break surfaces. If they vary the distance between the electrodes, the image charge is impacted and researches can control the energy levels of the molecule, determining the role of image charge in numerical terms.

Reference:

Perrin M.L., Verzijl C.J.O., Martin C.A. et al. Large tunable image-charge effects in single-molecule junctions. Nature Nanotechnology, 2013. DOI: 10.1038/nnano.2013