Linear side chains in benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c] pyrrole-4,6-dione polymers direct self-assembly and solar cell performance

Clement Cabanetos, Abdulrahman El Labban, Jonathan A. Bartelt, Jessica D. Douglas, William R. Mateker, Jean Frechet, Michael D. McGehee, Pierre Beaujuge

Research output: Contribution to journalArticlepeer-review

645 Scopus citations

Abstract

While varying the size and branching of solubilizing side chains in π-conjugated polymers impacts their self-assembling properties in thin-film devices, these structural changes remain difficult to anticipate. This report emphasizes the determining role that linear side-chain substituents play in poly(benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers for bulk heterojunction (BHJ) solar cell applications. We show that replacing branched side chains by linear ones in the BDT motifs induces a critical change in polymer self-assembly and backbone orientation in thin films that correlates with a dramatic drop in solar cell efficiency. In contrast, we show that for polymers with branched alkyl-substituted BDT motifs, controlling the number of aliphatic carbons in the linear N-alkyl-substituted TPD motifs is a major contributor to improved material performance. With this approach, PBDTTPD polymers were found to reach power conversion efficiencies of 8.5% and open-circuit voltages of 0.97 V in BHJ devices with PC71BM, making PBDTTPD one of the best polymer donors for use in the high-band-gap cell of tandem solar cells. © 2013 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)4656-4659
Number of pages4
JournalJournal of the American Chemical Society
Volume135
Issue number12
DOIs
StatePublished - Mar 19 2013

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KUS-C1-015-21
Acknowledgements: The authors acknowledge financial support under Baseline Research Funding from KAUST. Part of this work was supported by the Center for Advanced Molecular Photovoltaics (CAMP) (Award KUS-C1-015-21) made possible by KAUST. The authors thank KAUST Analytical Core Laboratories for mass spectrometry and elemental analyses and Dr. Michael Toney, Dr. Kristin Schmidt, and Dr. Christopher Tassone for their support with the GIXS experiments. Portions of this research were carried out at the Stanford Synchrotron Radiation Lightsource User Facility, operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences.

ASJC Scopus subject areas

  • Biochemistry
  • Colloid and Surface Chemistry
  • General Chemistry
  • Catalysis

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