Regensburg 2010 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 67: Organic Semiconductors: Solar Cells II (Joint Session with DS/CPP/O)
HL 67.6: Vortrag
Freitag, 26. März 2010, 11:45–12:00, H16
Role of the Charge Transfer State for Organic Solar Cells — •Carsten Deibel1, Alexander Wagenpfahl1, Thomas Strobel1,2, and Vladimir Dyakonov1,3 — 1Experimental Physics VI, Julius-Maximilians-University of Würzburg, Germany — 2(now at Cavendish Laboratory, University of Cambridge, UK) — 3Functional Materials for Energy Technology, Bavarian Centre for Applied Energy Research (ZAE Bayern), Würzburg, Germany
In organic bulk heterojunction solar cells, the charge transfer (CT) state is the intermediate but crucial step between exciton dissociation and charge transport to the electrodes. It is important for both, open circuit voltage and photocurrent.
The maximum open circuit voltage of organic bulk-heterojunction solar cells was recently shown to be given by the energy of the CT state (Nat. Mater. 8 (2009) 904). For P3HT:PCBM solar cells, it is around 1.1eV, whereas the open circuit voltage is only around 600 mV. This discrepancy was assigned to nonradiative recombination, although the details are still unknown. Performing macroscopic device simulations with input parameters resulting from a comprehensive experimental characterization, we discuss the relative contributions of surface and bulk recombination to this difference. Concerning the impact of the CT state on the photocurrent: we recently performed Monte Carlo simulations of CT dissociation, finding that the fast local charge carrier transport can explain the high quantum yields in polymer solar cells. Also, we were able to show that CT diffusion to the electrodes before complete dissociation is a potential loss mechanism.