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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 21: Organic Electronics and Photovoltaics III
CPP 21.10: Vortrag
Mittwoch, 24. März 2010, 12:00–12:15, H37
Stability optimisation of small molecule organic solar cells — •Martin Hermenau, Karl Leo, and Moritz Riede — Institut für Angewandte Photophysik, George-Bähr-Str. 1, 01069 Dresden
In addition to high efficiency and low cost, a long device lifetime is a crucially important factor for the commercialisation of small molecule organic solar cells. Previous results mostly covered unencapsulated devices and showed low lifetimes under 1000 hours even without permanent illumination.
Here, we present results on improving the intrinsic stability of glass-glass-encapsulated p-i-n solar cells containing small molecules. Zinc-Phthalocyanine and the fullerene C60 are used as photoactive materials. Doped layers of wide gap materials and C60 are used as hole and electron transport layer, respectively. All devices are illuminated with monochromatic or white LEDs and IV characteristics are automatically recorded during the entire measuring period.
In contrast to polymer solar cells, we do not observe an influence of different types of top contact materials on the lifetime. All variations of Gold, Silver and Aluminium lead to stable cells for about 1500 hours of continued illumination.
However, by changing the type and even the thickness of the hole transport material we are able to enhance the extrapolated lifetime (t80) from about 1100 hours with 30nm PV-TPD up to more than 5000 hours with 60nm Di-NPB. These results are achieved with encapsulated devices and illumination intensitites up to 840 mW/cm2 from high-power white LEDs at controlled temperatures of 50∘C.