Faculty of Engineering and Natural Sciences
Conjugated Dendrimers for Organic Photovoltaics
Muhammet Erkan Köse, Scientist II
National Renewable Energy Laboratory
In recent years, tremendous amount of research has focused on organic solar cells for converting sunlight directly into electricity. Organic solar cells are attractive because of their flexibility, ease of processing, and potential low cost manufacture. In this talk, an overview of recent experimental and theoretical results on photovoltaic properties of conjugated dendrimers will be given. Phenyl cored three-arm and four-arm thiophene dendrimers are promising donor materials for devices despite the fact that they possess optical band gaps ranging from 2.10 eV to 2.55 eV, making them poor solar absorbers. The photophysical properties as well as energy/charge transport mechanisms in the amorphous dendrimer films will be discussed. The simulated absorption/emission spectra of dendrimers show excellent agreement with the experimental data once the ab initio methods are utilized in the theoretical approach. The simulated exciton diffusion lengths are also in very good agreement with the experiment for the same materials. Monte-Carlo simulations reveal that the hole mobilities in four-arm dendrimers are larger than the electron mobilities. The simulations also indicate that the carrier mobilities do not vary significantly with the size of the dendrimer in four-arm series.
March 20, 2009, 14:40, FENS L048