Charge Generation Measured for Fullerene-Helical Nanofilament Liquid Crystal Heterojunctions

Rebecca A. Callahan, David C. Coffey, Dong Chen, Noel A. Clark, Garry Rumbles, David M. Walba

Research output: Contribution to journalArticlepeer-review

33 Scopus Citations


The helical nanofilament (HNF) liquid crystal phase is an ordered architecture exhibiting interesting properties for charge transport. It is a small molecule self-assembly of stacked and twisted crystalline layers, which form alignable organic nanorods with half the surface area of the filaments consisting of aromatic sublayer edges. HNFs mixed with an electron acceptor generate an intriguing network for photoinduced electron transfer (PET). In this work, we characterize the structure of the HNF phase as processed into thin films with transmission electron microscopy (TEM) and X-ray diffraction (XRD). Additionally, we measure the flash-photolysis time-resolved microwave conductivity (TRMC) in samples where the HNF phase is fabricated into heterojunctions with the fullerenes C60 and PC60BM, prototypical electron acceptors for organic photovoltaics. Two distinct microstructures of the thin films were identified and compared for PET. A near-unity charge generation yield is observed in a bilayer of HNFs with C 60. Moreover, the HNF phase is shown to be 10× better at charge generation than a lamellar structuring of the same components. Thus, the HNF phase is shown to be a good charge-generation interface.

Original languageAmerican English
Pages (from-to)4823-4830
Number of pages8
JournalACS Applied Materials and Interfaces
Issue number7
StatePublished - 2014

NREL Publication Number

  • NREL/JA-5900-61397


  • bulk heterojunction
  • charge generation
  • helical nanofilaments
  • liquid crystal
  • time-resolved microwave conductivity


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