One-dimensional self-confinement promotes polymorph selection in large-area organic semiconductor thin films

Gaurav Giri, Ruipeng Li, Detlef M. Smilgies, Er Qiang Li, Ying Diao, Kristina M. Lenn, Melanie Chiu, Debora W. Lin, Ranulfo Allen, Julia Reinspach, Stefan C.B. Mannsfeld, Sigurdur T. Thoroddsen, Paulette Clancy, Zhenan Bao, Aram Amassian

Research output: Contribution to journalArticlepeer-review


A crystal's structure has significant impact on its resulting biological, physical, optical and electronic properties. In organic electronics, 6,13(bis-triisopropylsilylethynyl)pentacene (TIPS-pentacene), a small-molecule organic semiconductor, adopts metastable polymorphs possessing significantly faster charge transport than the equilibrium crystal when deposited using the solution-shearing method. Here, we use a combination of high-speed polarized optical microscopy, in situ microbeam grazing incidence wide-angle X-ray-scattering and molecular simulations to understand the mechanism behind formation of metastable TIPS-pentacene polymorphs. We observe that thin-film crystallization occurs first at the air-solution interface, and nanoscale vertical spatial confinement of the solution results in formation of metastable polymorphs, a one-dimensional and large-area analogy to crystallization of polymorphs in nanoporous matrices. We demonstrate that metastable polymorphism can be tuned with unprecedented control and produced over large areas by either varying physical confinement conditions or by tuning energetic conditions during crystallization through use of solvent molecules of various sizes.

Original languageEnglish (US)
Article number3573
JournalNature communications
StatePublished - Apr 16 2014
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • General Biochemistry, Genetics and Molecular Biology
  • General Physics and Astronomy


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