A comparative study of fluorine substituents for enhanced stability of flexible and ITO-free high-performance polymer solar cells

Jon Eggert Carlé, Martin Helgesen, Natalia Klaudia Zawacka, Morten Vesterager Madsen, Eva Bundgaard, Frederik C Krebs

Research output: Contribution to journalJournal articleResearchpeer-review


Two low-band gap polymer series based on benzo[1,2-b:4,5-b?]dithiophene (BDT) and dithienylbenzothiadiazole, with different numbers of fluorine substituents on the 2,3,1-benzothiadiazole unit, have been synthesized and explored in a comparative study of the photochemical stability and operational lifetime in flexible large area roll-coated bulk heterojunction solar cells. The two polymer series have different side chains on the BDT unit, namely 2-hexyldecyloxy (BDTHDO) (P1-P3) or 2-hexyldecylthiophene (BDT THD) (P4-P6). The photochemical stability clearly shows that the stability enhances along with the number of fluorine atoms incorporated on the polymer backbone. Fabrication of the polymer solar cells based on the materials was carried out in ambient atmosphere on a roll coating/printing machine employing flexible and indium-tin-oxide-free plastic substrates. Solar cells based on the P4-P6 series showed the best performance, reaching efficiencies up to 3.8% for an active area of 1 cm2, due to an enhanced current compared to P1-P3. Lifetime measurements, carried out according to international summit on OPV stability (ISOS), of encapsulated devices reveals an initial fast decay for P1-P6 in the performance followed by a much slower decay rate, still retaining 40-55% of their initial performance after 250 h of testing under ISOS-L-1 conditions. © 2014 Wiley Periodicals, Inc.
Original languageEnglish
JournalJournal of Polymer Science. Part B, Polymer Physics
Issue number13
Pages (from-to)893-899
Publication statusPublished - 2014


  • aging
  • benzodithiophene
  • benzothiadiazole
  • conjugated polymers
  • fluorine
  • fluoropolymers
  • high performance
  • ITO-free
  • polymer solar cells
  • processing
  • roll coating
  • stability
  • Aging of materials
  • Coatings
  • Conjugated polymers
  • Convergence of numerical methods
  • Decay (organic)
  • Fluorine
  • Fluorine containing polymers
  • Heterojunctions
  • Processing
  • Rolls (machine components)
  • Solar cells
  • Tin oxides
  • Benzodithiophene
  • Benzothiadiazoles
  • Polymer Solar Cells
  • Roll coating
  • Stability


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