Dresden 2006 – scientific programme

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DS: Dünne Schichten

DS 24: Poster presentation

DS 24.30: Poster

Tuesday, March 28, 2006, 15:00–17:30, P2

Interfaces in Complex Organic Structures Investigated by Spectroscopic Ellipsometry — •Sascha Hermann, Ovidiu Gordan, Marion Friedrich, and Dietrich R.T. Zahn — Chemnitz University of Technology, Semiconductor Physics, D-09107 Chemnitz, Germany

Organic multilayers and mixed layers were prepared by organic molecular beam deposition in high vacuum on hydrogen passivated Silicon(111) substrates at room temperature. The structures consist either of N,N-Di(naphthalene-1-yl)-N,N‘-diphenyl-benzidine (α-NPD) and tris(8-hydroxyquinoline) aluminium (Alq₃) or 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) and copper phthalocyanine (CuPc). The samples were studied by spectroscopic ellipsometry in the range of 0.73 eV to 5 eV and infrared spectroscopy (IR). The optical response of the multilayers consisting of Alq₃ and α-NPD could be modelled using the isotropic dielectric functions of single layers assuming sharp interfaces. The PTCDA/CuPc multilayers were described using the anisotropic dielectric functions of the constituents including interface-mixing and surface roughness. The deviation between the best simulation and the experiment suggest an electronic interaction due to coupling between the π-orbitals of CuPc and PTCDA at the interfaces. This coupling influences the optical properties and the orientation of CuPc molecules.