Regensburg 2010 – scientific programme

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DS: Fachverband Dünne Schichten

DS 29: Poster: Molecular Spintronics, Biomolecular and Functional Organic Layers, Organic Electronics and Photovoltaics, Plasmonics and Nanophotonics, Organic Thin Films, Nanoengineered Thin Films, Thin Film Characterisation,

DS 29.31: Poster

Wednesday, March 24, 2010, 15:00–17:30, Poster A

Interface properties and electronic structure of PCPDTBT - a promising polymer for organic solar cells — Umut Aygül, •Fotini Petraki, Holger Hintz, Heiko Peisert, and Thomas Chassé — Institute of Physical and Theoretical Chemistry, University of Tübingen, Germany

Mankind's energy demand is steadily increasing. Novel techniques for environmental friendly energy conversion are therefore a challenging task. Organic solar cells based on donor-acceptor blends present a quite new approach, which posses a large market potential although their efficiency is rather low compared to their inorganic counterparts. In polymer based ``bulk heterojunction''-type solar cells so-called ``low bandgap'' materials are promising donor components in active layers. Low optical bandgap conjugated polymers may improve the efficiency of organic photovoltaic devices by increasing the absorption in the visible and near infrared region of the solar spectrum and by optimizing the offset of the LUMO (lowest unoccupied molecular orbital) energy levels of the donor and acceptor. A potential candidate in this context is Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b'] dithiophene)-alt-4,7(2,1,3-benzothiadiazole) (PCPDTBT). We study the electronic structure and interface properties to gold and ITO of PCPDTBT by X-ray and UV photoemission spectroscopies (XPS, UPS) as well as X-ray absorption spectroscopy (XAS). The energy level alignment points to charge transfer processes across the interface. In addition, strong chemical interactions occur which may have consequences for interface properties in devices.