Temperature-mediated polymorphism in molecular crystals: The impact on crystal packing and charge transport
AuthorsStevens, Loah A.
Goetz, Katelyn P.
Williamson, Rachel M.
Coropceanu, Veaceslav P.
Jurchescu, Oana D.
Collis, Gavin E.
KAUST DepartmentKAUST Solar Center (KSC)
Physical Sciences and Engineering (PSE) Division
Materials Science and Engineering Program
Online Publication Date2015-01-02
Print Publication Date2015-01-13
Permanent link to this recordhttp://hdl.handle.net/10754/564006
MetadataShow full item record
AbstractWe 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.
SponsorsThis work was supported by the Flexible Electronics Theme and is part of the CSIRO Future Manufacturing Flagship. We acknowledge financial support from the CSIRO Office of the Chief Executive program for Y.S. and G.C. Work at WFU was supported by the National Science Foundation, under Grant ECCS 1254757 and GRFP DGE-0907738. The work at Georgia Tech was supported in part by the National Science Foundation under Award No. DMR-1105147. Data for X-ray structure determination were collected on the MX2 beamline at the Australian Synchrotron, Victoria, Australia.
PublisherAmerican Chemical Society (ACS)
JournalChemistry of Materials