Temperature-mediated polymorphism in molecular crystals: The impact on crystal packing and charge transport

Loah A. Stevens, Katelyn P. Goetz, Alexandr Fonari, Ying Shu, Rachel M. Williamson, Jean-Luc Bredas, Veaceslav P. Coropceanu, Oana D. Jurchescu, Gavin E. Collis

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

We report a novel synthesis to ultra high purity 7,14-bis((trimethylsilyl)ethynyl)dibenzo[b,def]-chrysene (TMS-DBC) and the use of this material in the growth of single crystals by solution and vapor deposition techniques. We observe that the substrate temperature has a dramatic impact on the crystal growth, producing two distinct polymorphs of TMS-DBC; low temperature (LT) fine red needles and high temperature (HT) large yellow platelets. Single crystal X-ray crystallography confirms packing structures where the LT crystals form a 1D slipped-stack structure, while the HT crystals adopt a 2D brickwork motif. These polymorphs also represent a rare example where both are extremely stable and do not interconvert to the other crystal structure upon solvent or thermal annealing. Single crystal organic field-effect transistors of the LT and HT crystals show that the HT 2D brickwork motif produces hole mobilities as high as 2.1 cm2 V-1 s-1, while the mobility of the 1D structure is significantly lower, at 0.028 cm2 V-1 s-1. Electronic-structure calculations indicate that the superior charge transport in the brickwork polymorph in comparison to the slipped-stack polymorph is due to the presence of an increased dimensionality of the charge migration pathways.
Original languageEnglish (US)
Pages (from-to)112-118
Number of pages7
JournalChemistry of Materials
Volume27
Issue number1
DOIs
StatePublished - Jan 2 2015

ASJC Scopus subject areas

  • Materials Chemistry
  • Chemical Engineering(all)
  • Chemistry(all)

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