Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 31: Topical Session Photovoltaic Materials II

MM 31.6: Talk

Wednesday, March 24, 2010, 13:00–13:15, H4

Morphological study of Zinc-Phthalocyanine for organic solar cells — •Christoph Schünemann, Chris Elschner, Alexandr Levin, Karl Leo, and Moritz Riede — Institut für Angewandte Photophysik, TU Dresden, Germany

Phthalocyanines (Pc) are well known organic molecules and often used in the photoactive layer of small molecule organic solar cells. Reasons for the wide application of these organic semiconductors are their thermal stability, simple way of deposition and their common use as model system. However, the influence of the morphology on the electrical properties of organic solar cells has been investigated only rudimentary so far. In this work, the crystal structure, the growth and the stacking of Zinc-Pc molecules in thin films are investigated with x-ray diffraction (XRD) and x-ray reflection (XRR) methods. For this purpose, we varied the ZnPc film thickness from 5 nm up to 50 nm and the substrate temperature while deposition from room temperature up to 90 °C. Using XRR and atomic force microscopy, we found that the roughness of ZnPc increases with increasing substrate temperature and layer thickness. The XRD measurements show that the ZnPc layers are polycrystalline for all substrate temperatures and layer thickness. Analysing the XRD pattern we also found out, that the ZnPc films are triclinic and the atomic structure does not change with variation of the deposition parameters. The dislocation density and the microstrain in the ZnPc layer decreases with rising film thickness while the crystallite size is in the range of the layer thickness.