Electronic processes in conjugated diblock oligomers mimicking low band-gap polymers: Experimental and theoretical spectral analysis

Jodi M. Szarko, Brian S. Rolczynski, Jianchang Guo, Yongye Liang, Feng He, Michael William Mara, Luping Yu*, Lin X Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Conjugated oligomers containing a common central thienothiophene unit symmetrically connected to two identical thiophene oligomers were studied as model systems for a series of low bandgap organic diblock copolymers. The oligothiophene side chain fragments were varied in length as a means to tune the electronic coupling between the thienothiophene and oligothiophene moieties. The fragment length dependence of both the ground- and excited-state electronic and structural properties of a series of diblock oligomers were investigated in detail. The charge transfer character in these diblock oligomers, revealed by their optical absorption and fluorescence spectra, is responsible for their low band gap and energy gap tunability compared with their homooligomer counterparts. The electronic spectra and theoretical analysis indicate a partially localized central charge in the first excited state. Using experimental results and comparing them with theoretical calculations, we estimate that the electronic effects from a single thienothiophene unit spreads over seven to nine adjacent units through π-conjugation along the oligomers.

Original languageEnglish (US)
Pages (from-to)14505-14513
Number of pages9
JournalJournal of Physical Chemistry B
Volume114
Issue number45
DOIs
StatePublished - Dec 8 2010

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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