Study of local structure at crystalline rubrene grain boundaries via scanning transmission X-ray microscopy

Alexandre L. Foggiatto, Yasuo Takeichi, Kanta Ono, Hiroki Suga, Yoshio Takahashi, Michael A. Fusella, Jordan T. Dull, Barry P. Rand, Kentaro Kutsukake, Takeaki Sakurai

Research output: Contribution to journalArticle

Abstract

Rubrene is a promising and archetypal organic semiconductor owing to its high reported hole mobility. However, this high mobility only exists in its crystalline state, with orders of magnitude reduction in disordered films. Thus, as it pertains to thin film polycrystalline rubrene, it is important to understand structure and the presence of disordered regions at grain boundaries. Here, we use scanning transmission X-ray microscopy (STXM) to investigate polycrystalline rubrene thin films with either platelet or spherulite morphology. The STXM images allow us to distinguish and quantify the arrangement of the local structure in the crystal. The analysis suggests that the platelet film has more oriented molecules in the crystal than in the spherulite phase. Also, at spherulite grain boundaries, we reveal a high number of misaligned molecules compared to the smooth boundary in the platelet case, with grain boundary sinuosity of 0.045 ± 0.002 and 0.139 ± 0.002 μm for the platelet and spherulite cases, respectively, which help to explain the higher mobility in the former case.

Original languageEnglish (US)
Pages (from-to)315-320
Number of pages6
JournalOrganic Electronics
Volume74
DOIs
StatePublished - Nov 2019

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry
  • Electrical and Electronic Engineering

Keywords

  • Image analysis
  • Organic semiconductor
  • Rubrene
  • X-ray microscope

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