Thioalkyl-substituted benzothiadiazole acceptors: Copolymerization with carbazole affords polymers with large stokes shifts and high solar cell voltages

Abby Casey, Raja Shahid Ashraf, Zhuping Fei, Martin Heeney

Research output: Contribution to journalArticlepeer-review

65 Scopus citations

Abstract

Copolymers of carbazole and 4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (dTBT) incorporating thioalkyl (-SR) and alkoxy (-OR) solubilizing groups on the 2,1,3-benzothiazdiazole (BT) unit are synthesized and compared. The introduction of -SR and -OR groups onto the BT unit of the polymer was found to have different effects on the electronic properties of the polymers as well as the conformation of the polymer backbone. Large conformational changes between the ground state (GS) and excited state (ES) geometries of the polymers with -SR groups led to very large Stokes shifts of up to 224 nm. The polymer with -OR groups was found to have approximately double the photovoltaic efficiency at ∼4% compared to the polymers with -SR groups (PCE ∼ 2%). However, polymers with -SR groups were found to give very high open circuit voltages (VOC) of over 1 V. Changing the -SR chain length from ethyl to dodecyl was found to have little influence on the solar cell performance of the polymer or the magnitude of the Stokes shift. © 2014 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)2279-2288
Number of pages10
JournalMacromolecules
Volume47
Issue number7
DOIs
StatePublished - Apr 8 2014
Externally publishedYes

Bibliographical note

Generated from Scopus record by KAUST IRTS on 2023-02-14

ASJC Scopus subject areas

  • Materials Chemistry
  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry

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