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PGI-1 Seminar: Dr. Carina Faber

Ab initio GW and Bethe-Salpeter calculations for organic photovoltaic systems

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28 Jan 2015 11:30
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PGI Lecture Hall

ETH Zürich, Materials Theory Group

Abstract:

Photovoltaics represents one of the most promising routes towards a sustainable energy generation. Besides thin film technologies, photovoltaics based on organic semiconductors seems to be one of the most appealing concepts for a low-cost and clean energy production. However, the obtained efficiencies and lifetimes are still far from their theoretical limits.


First-principles quantum mechanical calculations contribute to this field not only by finding new efficient material combinations, but equally they allow to understand fundamental processes like photon absorption or charge separation in this special class of materials. Initially developed in the mideighties at the ab initio level for inorganic semiconductors, the many-body perturbation theory GW and Bethe-Salpeter (BSE) formalisms have recently been shown to yield electronic and optical properties of organic systems with a remarkable accuracy. After introducing some of the important limitations
associated with organic photovoltaic cells, we will show that key features, such as band gaps, electron-phonon coupling strengths and donor-to-acceptor charge-transfer excitations can be described with unprecedented accuracy. The used techniques are parameter-free and allow the study of systems comprising up to a few hundred of atoms. The selected calculations have been performed with a recently developed Gaussian-basis GW and BSE package, the Fiesta code.

Contact

Prof. Dr. Stefan Blügel
Phone: +49 2461 61-4249
Fax: +49 2461 61-2850
email: s.bluegel@fz-juelich.de

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