Grooved nanowires from self-assembling hairpin molecules for solar cells

Ian D. Tevis, Wei Wen Tsai, Liam C. Palmer, Taner Aytun, Samuel I. Stupp

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

One of the challenges facing bulk heterojunction organic solar cells is obtaining organized films during the phase separation of intimately mixed donor and acceptor components. We report here on the use of hairpin-shaped sexithiophene molecules to generate by self-assembly grooved nanowires as the donor component in bulk heterojunction solar cells. Photovoltaic devices were fabricated via spin-casting to produce by solvent evaporation a percolating network of self-assembled nanowires and fullerene acceptors. Thermal annealing was found to increase power conversion efficiencies by promoting domain growth while still maintaining this percolating network of nanostructures. The benefits of self-assembly and grooved nanowires were examined by building devices from a soluble sexithiophene derivative that does not form one-dimensional structures. In these systems, excessive phase separation caused by thermal annealing leads to the formation of defects and lower device efficiencies. We propose that the unique hairpin shape of the self-assembling molecules allows the nanowires as they form to interact well with the fullerenes in receptor-ligand type configurations at the heterojunction of the two domains, thus enhancing device efficiencies by 23%.

Original languageEnglish
Pages (from-to)2032-2040
Number of pages9
JournalACS nano
Volume6
Issue number3
DOIs
Publication statusPublished - Mar 27 2012

Keywords

  • morphology
  • nanowire
  • organogelator
  • photovoltaic
  • self-assembly
  • sexithiophene

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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