Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 26: Organic Photovoltaics I

CPP 26.9: Vortrag

Mittwoch, 25. März 2009, 16:00–16:15, ZEU 222

Transparent Metal Electrodes for Organic Solar Cells — •Jan Meiss, Moritz K. Riede, and Karl Leo — Institut fuer Angewandte Photophysik, Technische Universitaet Dresden, 01062 Dresden - http://www.iapp.de

Organic solar cells (OSC) are emerging as possible inexpensive alternative to inorganic photovoltaics. Current issues of OSC are the high price of indium tin oxide (ITO), the most commonly used transparent contacting material, and the fact that glass is used as substrate in almost all cases. We are exploring alternatives to the scarce and expensive ITO and investigate alternative OSC configurations, i.e. top-illuminated and inverted solar cells.

In this contribution, top-illuminated small-molecule organic solar cells with transparent metal cathodes consisting of different combinations of Al, Ag and Au are presented. The whole device stack has been prepared by thermal evaporation under vacuum. It is shown that multi-layer metal cathodes employing surface modifying interlayers achieve by far superior performance compared to single-layer cathodes. Scanning electron and atomic force microscopy show that this can be attributed to significantly improved morphology in multi-layer devices; these conclusions are supported by the electrical properties in the current-voltage curves. By additionally enhancing light incoupling with a capping layer and utilizing microcavity effects, promising efficiencies of over 2.2% are obtained for zinc phthalocyanine / C60 bulk heterojunction solar cells containing standard materials.