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Details of Grant 

EPSRC Reference: EP/H035184/1
Title: Medium effects in single molecule electronics
Principal Investigator: Higgins, Professor S
Other Investigators:
Nichols, Professor RJ
Researcher Co-Investigators:
Project Partners:
Department: Chemistry
Organisation: University of Liverpool
Scheme: Standard Research
Starts: 01 December 2010 Ends: 30 November 2014 Value (£): 325,979
EPSRC Research Topic Classifications:
Chemical Structure Electrochemical Science & Eng.
Surfaces & Interfaces
EPSRC Industrial Sector Classifications:
No relevance to Underpinning Sectors
Related Grants:
Panel History:
Panel DatePanel NameOutcome
24 Feb 2010 Physical Sciences Panel - Chemistry Announced
Summary on Grant Application Form
In silicon chip technology, increasingly sophisticated and expensive methods are being developed to carve smaller and smaller features into the silicon surface, to generate ever-smaller circuit components such as transistors. As the size of these features reaches the level of tens of nanometres, researchers are becoming ever more interested in the possibility of using assemblies of organic molecules as circuit components, even down to the level of single molecules. Very sophisticated molecules, designed to imitate simple circuit elements such as diodes, have been synthesised. But a key issue is the necessity to contact such molecules electrically - to 'wire' them into circuits. We, along with many other researchers worldwide, have been studying the properties of molecules terminated with sulfur atoms, which attach readily to gold surfaces. In our work, we have developed two related techniques for measuring the conductance of small integer numbers, n, of molecules, including n = 1. The molecules are sandwiched between two gold contacts. We do this by adapting the technique of scanning tunneling microscopy (STM), in which the position of an atomically-fine metal tip is controlled very precisely over a metal surface. With the right conditions, we can persuade sulfur-terminated molecules to bridge between the metal (gold) surface and the STM tip. We can then measure the current that flows through the molecule(s). Using this method, we recently discovered that the conductance of single molecules called oligothiophenes was several hundred times higher in the presence of water than when water was carefully excluded from the experiment. This is important for several reasons. Firstly, if the electrical properties of molecules depends on their environment, we will have to take care to exclude water in molecular electronics devices. But more intriguing, we could perhaps make very sensitive sensors by designing 'host' molecules that change their conductance on exposure to a particular target molecule.In this proposal, we seek to explore the origins of this 'medium' effect, and to examine how it can be controlled. We also want to find better ways to calculate the conductance of metal|molecule|metal junctions taking into account the presence of water, or other solvent ('medium') molecules.
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Organisation Website: http://www.liv.ac.uk