Charge Transfer between Semiconducting Substrates and Organic Molecules Robert Opila, University of

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Charge Transfer between Semiconducting Substrates
and Organic Molecules Robert Opila, University
of Delaware, Newark, DE 19711

• Molecular electronics is a promising field
  offering the potential to make electronic devices
  of single molecules. Our work focuses on
  understanding the charge transfer between a
  molecule and a substrate. Specifically, we are
  probing the alignment of electron energy levels
  between molecule and substrate, and the related
  conduction barriers. We have focused on two
  small molecules, phenylacetylene and styrene,
  which are prototypical electronic molecules, on
  silicon surfaces.

We have confirmed chemical binding of the two
molecules, and seen that the highest occupied
molecular orbitals align similarly with the
silicon valence band, with a barrier of 0.7 eV.
The lowest unoccupied molecular orbitals of these
two molecules, however, align differently, with a
barrier of 1.7 eV in the case of phenylacetylene
and above 2 eV in the case of styrene. This
understanding allows us to tailor
molecule/substrate interactions to optimize
charge transfer at the interface.