Post-deposition processing methods to induce preferential orientation in contorted hexabenzocoronene thin films

Anna M. Hiszpanski, Stephanie S. Lee, He Wang, Arthur R. Woll, Colin Nuckolls, Yueh Lin Loo

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

The structuring in organic electrically active thin films critically influences the performance of devices comprising them. Controlling film structure, however, remains challenging and generally requires stringent deposition conditions or modification of the substrate. To this end, we have developed post-deposition processing methods that are decoupled from the initial deposition conditions to induce different out-of-plane molecular orientations in contorted hexabenzocoronene (HBC) thin films. As-deposited HBC thin films lack any long-range order; subjecting them to post-deposition processing, such as hexanes-vapor annealing, thermal annealing, and physical contact with elastomeric poly(dimethyl siloxane), induces crystallization with increasing extents of preferential edge-on orientation, corresponding to greater degrees of in-plane π-stacking. Accordingly, transistors comprising HBC thin films that have been processed under these conditions exhibit field-effect mobilities that increase by as much as 2 orders of magnitude with increasing extents of molecular orientation. The ability to decouple HBC deposition from its subsequent structuring through post-deposition processing affords us the unique opportunity to tune competing molecule-molecule and molecule-solvent interactions, which ultimately leads to control over the structure and electrical function of HBC films.

Original languageEnglish (US)
Pages (from-to)294-300
Number of pages7
JournalACS Nano
Volume7
Issue number1
DOIs
StatePublished - Jan 22 2013
Externally publishedYes

Keywords

  • contorted hexabenzocoronene
  • organic thin-film transistor
  • post-deposition processing
  • preferential molecular orientation

ASJC Scopus subject areas

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

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