Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 41: Organic semiconductors

HL 41.7: Talk

Thursday, February 28, 2008, 16:45–17:00, ER 270

Influence of Dissociation and Recombination on the Photocurrent of Organic Bulk Heterojunction Solar Cells — •Carsten Deibel, Andreas Baumann, Thomas Strobel, and Vladimir Dyakonov — Experimental Physics VI, Julius-Maximilians-University of Würzburg, Am Hubland, D-97074 Würzburg

Despite the significant increase of performance of organic bulk heterojunction solar cells in recent years, the detailed knowledge of the relevant elementary processes remains under debate. Concerning charge carrier recombination, literature so far reports different mechanisms: monomolecular recombination or a combination of bimolecular recombination with thermalisation, or what is called dispersive recombination. In order to contribute to this discussion, we present investigations of the photocurrent of polymer:fullerene solar cells. We apply time-resolved as well as steady-state techniques such as photo-CELIV --- charge carriers generated by a short laser pulse are extracted after a variable delay time --- and current--voltage measurements, in dependence of temperature. In order to complement these experiments, we perform Monte Carlo simulations of polaron pair dissociation in disordered donor--acceptor systems, considering monomolecular and bimolecular recombination. Comparing the simulations to the experimental results, we discuss the impact of recombination mechanisms on the photocurrent.