Ladder-type nonacyclic structure consisting of alternate thiophene and benzene units for efficient conventional and inverted organic photovoltaics

Yen-Ju Cheng*, Chiu Hsiang Chen, Yu Shun Lin, Chih Yu Chang, Chain-Shu Hsu

*Corresponding author for this work

Research output: Contribution to journalArticle

48 Scopus citations

Abstract

A ladder-type nonacyclic thienyl-phenylene-thienylene-phenylene-thienyl TPTPT unit, consisting of alternate interfused thiophene and benzene units, is designed and synthesized. This multifused distannyl-TPTPT monomer was polymerized with two electron-deficient acceptors, 4,7-dibromo-2,1,3- benzothiadiazole BT and 5,8-dibromo-2,3-diphenylquinoxaline QX monomers, by Stille coupling reaction to afford two alternating donor-acceptor copolymers, PTPTPTBT and PTPTPTQX, respectively. Because of the covalent planarization of the conjugated framework, PTPTPTBT simultaneously possess excellent solubilities for solution-processability, low bandgaps with suitable position of HOMO/LUMO energy levels, and high hole mobilities. The devices based on the PTPTPTBT/PC71BM blend not only showed a promising PCE of 5.3% with conventional configuration but also achieved a high PCE of 5.9% with inverted configuration. This value is among the highest performance from the inverted solar cells incorporating a donor-acceptor low bandgap polymer.

Original languageEnglish
Pages (from-to)5068-5075
Number of pages8
JournalChemistry of Materials
Volume23
Issue number22
DOIs
StatePublished - 22 Nov 2011

Keywords

  • Ladder-type structure
  • alternating copolymer
  • organic photovoltaics

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