Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 26: Organic Photovoltaics I

CPP 26.10: Vortrag

Mittwoch, 25. März 2009, 16:15–16:30, ZEU 222

Effects of geminate and bimolecular recombination on the performance of polymeric-small molecular solar cells — •Marcel Schubert¹, Chunhong Yin¹, Mauro Castellani¹, Alan Sellinger², and Dieter Neher¹ — ¹University of Potsdam, Institute of Physics and Astronomy, 14476 Potsdam-Golm, Germany — ²IMRE and A*Star, 3 Research Link, 117602 Republic of Singapore

Many physical properties of organic photovoltaics are related to the nature of the geminate pair, an intermediate state that forms after dissociation of photogenerated excitons and prior to free charge carrier generation. Whereas it was found that photocurrent generation is dominated by the strong field dependent process of geminate pair dissociation, the recombination of uncorrelated free charge carriers and the formation of space charge seem to play a minor role in the prominent P3HT/PCBM combination. The situation may change, when using different D/A combinations or other soluble acceptor molecules.

We present organic solar cells comprising a novel small molecule based on 2-vinyl-4,5-dicyanoimidazole (Vinazene) as acceptor and M3EH-PPV as donor. While bilayer devices show promising results with a fill factor up to 57 %, the IU-characteristics of bulk heterojunction devices are dominated by bimolecular recombination and space charge effects even at moderate illumination intensities. Photo-CELIV measurements were performed to study the bimolecular recombination in detail. By combining photo-CELIV results with PL and IU measurements we are able to analyze the interrelation of recombination losses, free charge carrier generation and exciplex formation.