Charge Delocalization in Oligomers of Poly(2,5-bis(3-Alkylthiophene-2-yl)thieno[3,2-b]thiophene) (PBTTT)

Yuexing Zhang, Robert Steyrleuthner, Jean Luc Bredas

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

We investigate theoretically charge delocalization in radical cations, i.e., positive polarons, formed on oligomer chains of poly(2,5-bis(3-Alkylthiophene-2-yl)thieno[3,2-b]thiophene) (PBTTT). We use nonempirically tuned range-separated density functionals (TRS-DFT), including LC-?PBE, LC-BLYP, and ?B97XD. We consider the evolution with oligomer length of the molecular geometric and electronic structures, optical absorption features, and spin densities. The TRS-DFT results indicate that a positive polaron can delocalize ideally over some 10 thiophene rings when the backbone is nonplanar and up to 14 rings for a backbone forced to be completely planar. Interestingly, up to six polarons can coexist side-by-side in a hexamer (which contains 24 thiophene rings), which is consistent with the highest degrees of doping (oxidation) experimentally achievable in polythiophene derivatives.

Original languageEnglish (US)
Pages (from-to)9671-9677
Number of pages7
JournalJournal of Physical Chemistry C
Volume120
Issue number18
DOIs
StatePublished - May 12 2016
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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