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Influence of different copolymer sequences in low band gap polymers on their performance in organic solar cells

: Lange, A.; Krueger, H.; Ecker, B.; Tunc, A.V.; Hauff, E. von; Morana, M.


Journal of polymer science. A, polymer chemistry 50 (2012), Nr.8, S.1622-1635
ISSN: 0360-6376
ISSN: 0887-624X
ISSN: 1099-0518
ISSN: 1096-990X
Fraunhofer IAP ()

The chemical design of a polymer can be tailored by a random or a block sequence of the comonomers in order to influence the properties of the final material. In this work, two sequences, PCPDTBT and F8BT (F8), were polymerized to form a block or a random copolymer. Differences between the various polymers were examined by exploring the surface topography and charge carrier mobility. A distinct surface texture and a higher charge carrier mobility was found for the block copolymer with respect to the other materials. Solar cells were prepared with polymer:PC 71BM blend active layers and the best performance of up to 2% was found for the block copolymer, which was a direct result of the fill factor. Overall, the sequences of different copolymers for solar cell applications were varied and a positive impact on efficiency was found when the block copolymer structure was utilized.