Regensburg 2010 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 35: Biomolecular and Functional Organic Layers I (Focused Session)
DS 35.4: Vortrag
Donnerstag, 25. März 2010, 18:15–18:30, H2
Optical Properties of Thin Films of ZnTPP oligomers — •Simona Pop1, Mathias Senge2, Oliver Locos2, Karsten Hinrichs1, Xin Zhang3, Jörg Rappich3, Christoph Cobet1, and Norbert Esser1 — 1ISAS-Institute for Analytical Sciences, Albert-Einstein-Str.9, D-12489 Berlin, Germany — 2School of Chemistry, SFI Tetrapyrrole Laboratory, Trinity College Dublin, Dublin 2, Ireland — 3Helmholtz-Zentrum Berlin for Materials and Energy GmbH, Institute for Silicon Photovoltaics, Kekuléstrasse 5, D-12489 Berlin, Germany
Porphyrin oligomers are of great interest for technological applications such as biosensors, solar cells and OFETs (organic field-effect transistors). These materials exhibit extraordinary optical and electronic properties due to the π-conjugation. The main characteristics of these oligomers as a consequence of π-conjugation are the high polarisabilities and low energy electronic transitions. Here, thin films of ZnTPP (zinc tetraphenylporphyrin) monomer and dimer were investigated by means of spectroscopic ellipsometry. In the case of the π-conjugated ZnTPP dimer, the porphyrin units are connected through an ethylene bridge. The films were prepared by means of spin-coating method on silicon substrates. The dielectric functions of ZnTPP monomer and dimer are derived from ellipsometrical measurements by employing a three-phase optical model. As expected, the ZnTPP dimer films exhibit a strong red-shift of the first absorption structure, namely Q-band, compared to the monomer case. The spectral changes observed for the ZnTPP dimer films can be interpreted in terms of strong electronic interactions and weak electrostatic ones.