Molecular Electronics

 

The idea to use a single organic molecule with tailored electronic structure as an electronic device was first proposed by Aviram and Ratner in 1974. Although the challenge of integrating a single molecule into a macroscopic electric circuit seemed insurmountable at the time, recent developments in nanotechnology allow us to explore this idea experimentally.

The original Aviram-Ratner rectifier molecule consisted of a very strong electron donor (tetrathiafulvalene, TTF) and a very strong electron acceptor (tetracyanoquinodimethane, TCNQ) covalently linked in one molecule. Such a structure should have a very low HOMO-LUMO gap which was considered essential for effective current rectification (that is, asymmetric current flow through the molecule). However, synthesis of such molecules has been an elusive goal for a long time, since strong donor-acceptor interaction and electron transfer between the two parts of the molecule complicated the coupling reaction and subsequent purification. We have pioneered the synthesis of organic molecules with HOMO-LUMO gap below 0.3 eV, including the long-sought TTF-TCNQ dyad.

Using Langmuir-Blodgett deposition technique of the synthesized donor-acceptor amphiphiles, we have prepared molecular monolayers on a surface of gold, and, employing mercury drop as a second electrode, have demonstrated diode-like properties (current rectification) in such molecules.

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We continue exploring the field by synthesis of more robust rectifying molecules, molecules with switching capabilities, embedding "sticky" groups (such as thiols) for selective self-assembly on electrodes, making molecules with controlled dipole moment for fundamental studies of electron injection at the molecule/electrode interface, etc (see below). In collaboration with other groups, we use scanning probe techniques to interrogate the electrical and electronmechanic properties of single molecules.

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Recent papers:

New Stable Donor-Acceptor Dyads for Molecular Electronics,
M. Kondratenko, A. Moiseev, D.F. Perepichka*, J. Mater. Chem. 2011, 21, 1470-1478.

Self-Assembled Monolayers of Strong Electron Acceptors: Polynitrofluorenes on Gold,
D.F.Perepichka, M.Kondratenko, M.R.Bryce , Langmuir 2005 , 21, 8824-8831.

The first studies of a tetrathiafulvalene -σ- acceptor molecular rectifier,
G. Ho, J. Heath, M. Kondratenko, D. F. Perepichka, K. Arseneault, M. Pezolet, M. R. Bryce, Chem. Eur . J. 2005, 11 , 2914-2922. ( VIP and cover article )

Molecules With Exceptionally Low HOMO-LUMO Gap,
D.F.Perepichka, M.R.Bryce, Angew. Chem. Int. Ed. 2005 , 44 , 5370-5373.

Other Research fields: