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 Brédas, Veaceslav Coropceanu, Oana D. Jurchescu, Gavin E. Collis

Research output: Contribution to journalArticlepeer-review

63 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 13 2015
Externally publishedYes

ASJC Scopus subject areas

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

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