Impact of Atomistic Substitution on Thin-Film Structure and Charge Transport in a Germanyl-ethynyl Functionalized Pentacene

Jeni C. Sorli, Qianxiang Ai, Devin B. Granger, Kaichen Gu, Sean Parkin, Karol Jarolimek, Nicholas Telesz, John E. Anthony, Chad Risko, Yueh Lin Loo

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Functionalization of organic semiconductors through the attachment of bulky side groups to the conjugated core has imparted solution processability to this class of otherwise insoluble materials. A consequence of this functionalization is that the bulky side groups impact the solid-state packing of these materials. To examine the importance of side-group electronic character on accessing the structural phase space of functionalized materials, germanium was substituted for silicon in triisopropylsilylethynylpentacene (TIPS-Pn) to produce triisopropylgermanylethynylpentacene (TIPGe-Pn), with the TIPGe side group comparable in size to TIPS, but higher in electron density. We find TIPGe-Pn single crystals exhibit slip-stack, herringbone, and brickwork packing motifs depending on growth conditions, a stark contrast to TIPS-Pn, which accesses only the brickwork packing motif in both single crystals and thin films. Polycrystalline thin films of TIPGe-Pn exhibit two new, unidentified polymorphs from spin-coating and postdeposition annealing. Our experiments suggest that access to the structural phase space is not guided solely by the size of the side group; the electronic character of the side group in functionalized compounds also plays a significant role. As such, simple atomistic substitutions can cause significant differences in the accessible solid structures.

Original languageEnglish (US)
Pages (from-to)6615-6623
Number of pages9
JournalChemistry of Materials
Volume31
Issue number17
DOIs
StatePublished - Sep 10 2019

All Science Journal Classification (ASJC) codes

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

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