Regensburg 2002 – wissenschaftliches Programm

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SYOH: Organische Halbleiter

SYOH V: HV V

SYOH V.1: Hauptvortrag

Montag, 11. März 2002, 15:20–16:00, H37

Operation Principles of Polymer Based Bulk Heterojunction Solar Cells — •Christoph J. Brabec — SIEMENS CT MM1

It is intriguing to think of photovoltaic elements based on thin plastic films. The flexibility of chemical tailoring of desired properties, as well as the cheap technology already well developed for all kinds of plastic thin film applications would make such an approach a sure hit. The mechanical flexibility of plastic materials is welcome for all photovoltaic applications onto curved surfaces for architectural integration. By casting semitransparent plastic photovoltaic thin films between insulating window glasses, large unused areas can be accessed in addition to the limited roof areas of crowded cities. Even the color of such photovoltaic elements can be varied by sacrifying some parts of the visible solar spectrum, which is a long time desire of environmentally active designers and architects. All in all it is quite worthwhile to follow such a vision in research and development. The question is: where are we now? Nevertheless, many physical aspects of these bulk heterojunction solar cells are still under discussion, like the origin for the selection principle of the carriers, the open circuit voltage or the observed temperature dependence. An encouraging breakthrough to higher efficiencies has been realized by optimizing the complex phase structure of the electron-donor type polymers and electron-acceptor type fullerene blends. Further improvements can be expected based on the solid understanding of the interplay between photophysics, morphology and, in detail, transport. In this contribution we discuss the working principles of conjugated polymer / acceptor based solar cells and suggest a model for these types of devices.