Dresden 2009 – wissenschaftliches Programm
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SYOP: Symposium Organic Photovoltaics: From Single Molecules to Devices
SYOP 4: Organic Photovoltaics: from Single Molecules to Devices
SYOP 4.60: Poster
Donnerstag, 26. März 2009, 16:30–19:00, P1A
Electrical modeling of organic solar cells — •Wolfgang Tress, Moritz Riede, and Karl Leo — TU Dresden Institut für Angewandte Photophysik, George-Bähr-Straße 1, 01069 Dresden
We report on realistic modeling of small molecule solar cells based on ZnPc/C60. For this purpose, samples with systematically varied parameters like layer thicknesses are prepared in a pin structure, i.e. active layer(s) sandwiched in between doped transport layers.
For a comprehensive description of the whole solar cell stack, a drift-diffusion model has been developed to simulate the current-voltage characteristics of organic solar cells. As input an exciton profile is used, obtained from optical modeling via a thin-film-optics algorithm. In the electrical simulation, Poisson, transport, and continuity equations for electrons and holes are solved numerically under boundary conditions describing the contacts. The iterative algorithm itself is based on [1]. The multi-layer structures are treated using different recombination and mobility models, modified Onsager theory for charge carrier dissociation, and tunneling assisted barrier crossing. Additionally exciton processes like diffusion and quenching are implemented.
The experimental data is compared to simulation results, where parameter variations allow to estimate the influence of distinct effects. Different recombination and mobility models are evaluated and the limitations of the models shown. Finally, values for exciton diffusion lengths and other electrical properties of the used materials can be extracted.
[1] J. Staudigel et al, J. Appl. Phys. 86, 3895 (1999)