Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 45: Joint Poster Session

HL 45.12: Poster

Dienstag, 15. März 2011, 18:00–21:00, P1

Structural properties of thin films of organic charge transfer complexes — •Diana Nanova¹, Sebastian Beck¹, Milan Alt¹, and Michael Kröger^2,3 — ¹Kirchhoff-Institut für Physik, Universität Heidelberg — ²InnovationLab GmbH, Heidelberg — ³Institut für Hochfrequenztechnik, TU Braunschweig

Charge transfer (CT) complexes in the presented context are a mixture of two different types of molecules, one with electron accepting properties and one acting as a donor, which induces a charge transfer between the molecules. The band gap as well as the electronic and optical properties of the CT- compound depends on the degree of charge transfer. Mixing two CT-complexes at different concentrations by substituting only the acceptor molecules, might allow adjustment of the band gap and the optical properties in analogy to inorganic III-V semiconductor compounds. These materials could be applied in organic field-effect transistors or organic photovoltaic cells. Due to the importance of thin film deposition techniques for organic electronic devices we studied the growth of CT-compounds, like tetrathiafulvalene, tetracyanquinodimethane and its derivatives by thermal evaporation. The morphology of the films was investigated with atomic force microscopy and X-Ray diffraction on different substrates. To gain information about the electronic structure, we used ultra violet photoelectron spectroscopy and inverse photoelectron spectroscopy. We determined the degree of charge transfer in the complexes with infrared-spectroscopy using the linear relationship between the shift in the excitation energy of the C-N- stretching mode of the acceptor and the charge transfer.