π-conjugated polymer-fullerene covalent hybrids via ambient conditions Diels-Alder ligation

Basit Yameen, Tanja Puerckhauer, Jens Ludwig, Ishtiaq Ahmed, Ozcan Altintas, Ljiljana Fruk, Alexander Colsmann, Christopher Barner-Kowollik

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The established ability of graphitic carbon-nanomaterials to undergo ambient condition Diels-Alder reactions with cyclopentadienyl (Cp) groups is herein employed to prepare fullerene-polythiophene covalent hybrids with improved electron transfer and film forming characteristics. A novel precisely designed polythiophene (M n 9.8 kD, D strok sign 1.4) with 17 mol% of Cp-groups bearing repeat unit is prepared via Grignard metathesis polymerization. The UV/Vis absorption and fluorescence (λex 450 nm) characteristics of polythiophene with pendant Cp-groups (λmax 447 nm, λe-max 576 nm) are comparable to the reference poly(3-hexylthiophene) (λmax 450 nm, λe-max 576 nm). The novel polythiophene with pendant Cp-groups is capable of producing solvent-stable free-standing polythiophene films, and non-solvent assisted self-assemblies resulting in solvent-stable nanoporous-microstructures. 1H-NMR spectroscopy reveals an efficient reaction of the pendant Cp-groups with C60. The UV/Vis spectroscopic analyses of solution and thin films of the covalent and physical hybrids disclose closer donor-acceptor packing in the case of covalent hybrids. AFM images evidence that the covalent hybrids form smooth films with finer lamellar-organization. The effect is particularly remarkable in the case of poorly soluble C60. A significant enhancement in photo-voltage is observed for all devices constituted of covalent hybrids, highlighting novel avenues to developing efficient electron donor-acceptor combinations for light harvesting systems. Fullerene-polythiophene covalent-hybrids are achieved by exploiting the natural ability of pristine carbon nanomaterials to undergo ambient condition Diels-Alder reactions with cyclopentadienyl (Cp) groups. A novel polythiophene with pendant Cp-groups prepared via GRIM polymerization is employed to fabricate these covalent-hybrids that exhibit a higher extent of fluorescence quenching and smoother films with fine lamellar texture compared to physical hybrids.

Original languageEnglish (US)
Pages (from-to)3091-3098
Number of pages8
JournalSmall
Volume10
Issue number15
DOIs
StatePublished - Aug 13 2014

Keywords

  • Diels-Alder ligation
  • covalent nanohybrids
  • fullerenes
  • polythiophene

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