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HL: Fachverband Halbleiterphysik

HL 68: Photovoltaics: Organic Semiconductors

HL 68.5: Vortrag

Mittwoch, 28. März 2012, 18:45–19:00, ER 270

Recombination Processes in Disordered Organic Bulk-Heterojunction Solar Cells — •Alexander Wagenpfahl¹, Carsten Deibel¹, and Vladimir Dyakonov^1,2 — ¹Experimental Physics VI, Julius-Maximilians-University of Würzburg, 97074 Würzburg, Germany — ²Bavarian Centre for Applied Energy Research (ZAE Bayern), 97074 Würzburg, Germany

In recent years the charge carrier recombination mechanisms in organic bulk-heterojunction solar cells have been controversially discussed. For blended organic semiconductors recombination orders between one, two or even higher have been reported. The origin of these observations, the recombination pathways as well as their impact on the device performance, still need further investigations to be understood in detail. In an organic bulk-heterojunction solar cell two blended but spatially separated semiconductor phases are used to gain current from the incident light. Due to their spatial disorder organic semiconductors generally show a Gaussian distribution of the molecular orbitals. Introducing this disorder into our macroscopic numerical device simulation, we show the possible interaction pathways of conducting and trapped electrical charges within the multiple trapping and release model. Based on these results we illustrate the impact of various recombination pathways for charge carriers on the observed current-voltage characteristics under consideration of phase separation aspects. Our results clearly show that it is crucial for the performance which recombination pathway is dominant in organic bulk-heterojunction solar cells and which role the energetic disorder plays in these processes.