1. Structural correlations in the generation of polaron pairs in low-bandgap polymers for photovoltaics
- Author
-
Sybille Allard, Seyfullah Yilmaz, Thomas Limmer, Raphael Tautz, Hans-Joachim Egelhaaf, Jochen Feldmann, Enrico Da Como, David Beljonne, Vincent Lemaur, Elizabeth von Hauff, Ullrich Scherf, Ines Dumsch, Photo Conversion Materials, LaserLaB - Energy, and Publica
- Subjects
Organic electronics ,Multidisciplinary ,Materials science ,business.industry ,Band gap ,General Physics and Astronomy ,General Chemistry ,Conjugated system ,Polaron ,Acceptor ,General Biochemistry, Genetics and Molecular Biology ,Semiconductor ,Photovoltaics ,Electron affinity ,Optoelectronics ,SDG 7 - Affordable and Clean Energy ,business - Abstract
Polymeric semiconductors are materials where unique optical and electronic properties often originate from a tailored chemical structure. This allows for synthesizing conjugated macromolecules with ad hoc functionalities for organic electronics. In photovoltaics, donor-acceptor co-polymers, with moieties of different electron affinity alternating on the chain, have attracted considerable interest. The low bandgap offers optimal light-harvesting characteristics and has inspired work towards record power conversion efficiencies. Here we show for the first time how the chemical structure of donor and acceptor moieties controls the photogeneration of polaron pairs. We show that co-polymers with strong acceptors show large yields of polaron pair formation up to 24% of the initial photoexcitations as compared with a homopolymer (eta=8%). pi-conjugated spacers, separating the donor and acceptor centre of masses, have the beneficial role of increasing the recombination time. The results provide useful input into the understanding of polaron pair photogeneration in low-bandgap co-polymers for photovoltaics.
- Published
- 2012
- Full Text
- View/download PDF