Electro-optical modeling of bulk heterojunction solar cells

Kirchartz, T.; Taretto, K.; Pieters, B.E.; Rau, U.

doi:10.1063/1.3013904

Journal Article

PreJuSER-2571

Electro-optical modeling of bulk heterojunction solar cells

Kirchartz, T.FZJ* ; Pieters, B. E.FZJ* ; Taretto, K. ; Rau, U.FZJ*

2008
American Institute of Physics Melville, NY

Journal of applied physics 104, (2008) [10.1063/1.3013904]

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Please use a persistent id in citations: http://hdl.handle.net/2128/17274 doi:10.1063/1.3013904

Abstract: We introduce a model for charge separation in bulk heterojunction solar cells that combines exciton transport to the interface between donor and acceptor phases with the dissociation of the bound electron/hole pair. We implement this model into a standard semiconductor device simulator, thereby creating a convenient method to simulate the optical and electrical characteristics of a bulk heterojunction solar cell with a commercially available program. By taking into account different collection probabilities for the excitons in the polymer and the fullerene, we are able to reproduce absorptance, internal and external quantum efficiency, as well as current/voltage curves of bulk heterojunction solar cells. We further investigate the influence of mobilities of the free excitons as well as the mobilities of the free charge carriers on the performance of bulk heterojunction solar cells. We find that, in general, the highest efficiencies are achieved with the highest mobilities. However, an optimum finite mobility of free charge carriers can result from a large recombination velocity at the contacts. In contrast, Langevin-type of recombination cannot lead to finite optimum mobilities even though this mechanism has a strong dependence on the free carrier mobilities. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3013904]

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