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TT: Fachverband Tiefe Temperaturen

TT 35: TR: Nanoelectronics III: Molecular Electronics 1

TT 35.6: Vortrag

Donnerstag, 25. März 2010, 15:15–15:30, H21

Transport properties of CuPc based devices — •Cosima Schuster — Institut für Physik, Universität Augsburg, D-86135 Augsburg

Electronic structure and transport properties of copper phthalocyanine (CuPc), an organic semiconductor, are investigated using density functional theory and scattering theory combined with the non-equilibriums Green's function formalism. Mainly, we discuss the electronic structure of CuPc attached to gold chains -- a prototypical one-dimensional molecular device, which shall serve as model system for CuPc in transistors. There, electron and hole transport with different tranport properties is observed depending on the geometry and material of the contacts.

We determine, in particular, the charge density of the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital). Attached to leads, electrons are transfered to/from the leads, respectively, depending on the contact geometry. For a planar contact, the electron transport properties are intrinsic properties of the molecule and do not depend on the contact material. On the other hand, molecules contacted in perpendicular geometry, become hole doped. The transmission through the molecules does not only depend on the density of states of the device but also on the spatial overlap of molecular orbitals and leads in transport direction. Molecular orbitals localized on the Cu thus do not contribute to the transport in planar geometry, but provide the transmitting channel in perpendicular contact geometry.