Effects of bridging atom and π-bridge length on physical and photovoltaic properties of A-π-D-π-A oligomers for solution-processed organic solar cells

Y.N. Luponosov, J. Min, A.V. Bakirov, P.V. Dmitryakov, S.N. Chvalun, S.M. Peregudova, T. Ameri, C.J. Brabec, S.A. Ponomarenko

Research output: Contribution to journalArticlepeer-review

Abstract

Abstract Synthesis of novel acceptor-donor-acceptor oligomers with electron-withdrawing alkyldicyanovinyl groups linked through an oligothiophene π-bridge with either dithienosilole or cyclopentadithiophene electron donor units is described. Changing the bridgehead atom from carbon to silicon in the central donor unit leads to a significant change in optical, thermal and structural properties of the oligomers. In addition, elongation of the oligothiophene π-bridge in the oligomers increases energies of HOMO and LUMO levels and leads to an unexpected hypsochromic shift of their absorption spectrum, because extension of the conjugation length cannot compensate a decrease of the intramolecular charge transfer between the dithienosilole and dicyanovinyl units. Although these minor changes in the chemical structures have a pronounced impact on the morphologies of their blends with PC70BM, the optimized solution-processed organic solar cells based on these small molecules demonstrate similar power conversion efficiencies. © 2015 Elsevier Ltd.
Original languageEnglish
Pages (from-to)213-223
Number of pages11
JournalDyes and Pigments
Volume122
DOIs
Publication statusPublished - 2015

Keywords

  • Absorption spectroscopy
  • Carbon
  • Charge transfer
  • Crystal atomic structure
  • Oligomers
  • Photovoltaic effects
  • Solar power generation
  • Alkyldicyanovinyl groups
  • Dithienosilole
  • Donor acceptors
  • Heteroatom substitution
  • Oligothiophenes
  • Organic solar cell
  • Solar cells

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