Thermal conversion of precursor polymer to low bandgap conjugated polymer containing isothianaphthene dimer subunits

  • Umeyama T
  • Hirose K
  • Noda K
 et al. 
  • 24

    Readers

    Mendeley users who have this article in their library.
  • 11

    Citations

    Citations of this article.

Abstract

Thermal conversion strategy has been utilized in the synthesis of a novel low bandgap polymer containing isothianaphthene (ITN) dimer structure and benzodithiophene (BDT) unit in the backbone (PBIBDT). First, a highly soluble precursor polymer with an alternating main chain structure of bicyclo[2.2.2]octadiene-fused thiophene dimer and BDT (PPBIBDT) was synthesized by a palladium(0)-catalyzed Stille coupling reaction. Then, heating of the yellow PPBIBDT film spin-coated on a glass plate yielded a dark blue film of PBIBDT that was insoluble in any organic solvents. Thermogravimetric analysis of PPBIBDT showed 14% weight loss with an onset at 230 °C, corroborating the occurrence of the thermally induced retro-Diels?Alder reaction. The PBIBDT film showed red-shifted, broad absorption in the visible and near-infrared regions with a maximum at 706 nm compared to the precursor polymer PPBIBDT with an absorption peak at 445 nm. The introduction of an ITN dimer unit in the backbone lowered the bandgap owing to the stabilized quinoid resonance structure. The field-effect hole mobility of PBIBDT was determined to be 1.1 ? 10?4 cm2 V?1 s?1 with an on?off ratio of 2.5 ? 102, while the PPBIBDT-based device revealed no p- and n-type responses. Organic photovoltaic devices were fabricated based on the planar heterojunction structure of PBIBDT and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and showed a power conversion efficiency of 0.07% under standard AM1.5 sunlight (100 mW cm?2). These results obtained here will provide fundamental information on the design of thermally induced low bandgap polymers for device applications.
Thermal conversion strategy has been utilized in the synthesis of a novel low bandgap polymer containing isothianaphthene (ITN) dimer structure and benzodithiophene (BDT) unit in the backbone (PBIBDT). First, a highly soluble precursor polymer with an alternating main chain structure of bicyclo[2.2.2]octadiene-fused thiophene dimer and BDT (PPBIBDT) was synthesized by a palladium(0)-catalyzed Stille coupling reaction. Then, heating of the yellow PPBIBDT film spin-coated on a glass plate yielded a dark blue film of PBIBDT that was insoluble in any organic solvents. Thermogravimetric analysis of PPBIBDT showed 14% weight loss with an onset at 230 °C, corroborating the occurrence of the thermally induced retro-Diels?Alder reaction. The PBIBDT film showed red-shifted, broad absorption in the visible and near-infrared regions with a maximum at 706 nm compared to the precursor polymer PPBIBDT with an absorption peak at 445 nm. The introduction of an ITN dimer unit in the backbone lowered the bandgap owing to the stabilized quinoid resonance structure. The field-effect hole mobility of PBIBDT was determined to be 1.1 ? 10?4 cm2 V?1 s?1 with an on?off ratio of 2.5 ? 102, while the PPBIBDT-based device revealed no p- and n-type responses. Organic photovoltaic devices were fabricated based on the planar heterojunction structure of PBIBDT and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and showed a power conversion efficiency of 0.07% under standard AM1.5 sunlight (100 mW cm?2). These results obtained here will provide fundamental information on the design of thermally induced low bandgap polymers for device applications.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

Authors

  • Tomokazu Umeyama

  • Kohei Hirose

  • Kei Noda

  • Kazumi Matsushige

  • Tetsuya Shishido

  • Hironobu Hayashi

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free