Thomas Bj�rnholm
Nano Science Center, University of Copenhagen
Organic molecules in electronic devices

Organic molecules are becoming increasingly important as the active component in electronic devices both in the form of low-tech high market volume applications (e.g. organic light emitting diodes) and, on a single molecule level, in basic research test systems. In both cases the ability to structurally organize and inter-connect the molecular constituents is a central issue, which requires a successful combination of molecular self-organization and lithography. The talk will highlight recent results on single molecule single electron transistors (1), self-assembly of gold nanoparticles into molecular electronic circuitry (2-5), structural nanoscale studies of self-assembled biologically relevant systems (5-6), self-organized electronic thin films (7), and organic synthesis of thiol end-capped p-systems (8). Our most recent results on electrical transport at 4 Kelvin through a single oligo-p-phenylenevinylene molecule placed in a gap of about 2 nm between source and drain electrode of a single electron transistor device (SET) will be given special emphasis (1). The measurements reveal for the first time the relation between transistor characteristics and the position of the molecular redox states which are strongly influenced by image charges in the electrodes.
References:
[1] S. Kubatkin, T. Bj�rnholm et al. Nature 425 698 (2003).
[2] T. Hassenkan, M. Brust, T. Bj�rnholm et al. Adv. Mat. 14 1126-1130 (2002).
[3] K. N�rgaard, M. Brust, T. Bj�rnholm et al. Faraday Discussions 125 221-233 (2004).
[4] T. Hassenkam, T. Bj�rnholm et al. Nano Letters 4 19 (2004)
[5] T. R. Jensen, K. Kj�r, T. Bj�rnholm et al. Phys. Rev. Lett. 90 086101 (2003); P. Ball, News & Views, Nature 423 25-26 (2003).
[6] L. K. Nielsen, T. Bj�rnholm, O.G. Mouritsen, Nature 404 352 (2000).
[7] B. W. Lauersen, T. Bj�rnholm, et al. Langmuir, in press (2004).
[8] N. Stuhr-Hansen, T. Bj�rnholm et al. J. Org. Chem. 68 1275 (2003).