Influences of Structural Modification of S, N-Hexacenes on the Morphology and OFET Characteristics

Yi Fan Huang, Chun Kai Wang, Bo Han Lai, Chin Lung Chung, Chin Yi Chen, Guan Ting Ciou, Ken Tsung Wong*, Chien-Lung Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Although chemical modifications on conjugated molecules are widely applied for the purpose of improving processability and device performances, the effect of the modification was far less investigated. Here, five S,N-hexacenes are studied to reveal the influences of (1) the lateral alkyl chain, (2) the terminal group (thiophene vs benzene), and (3) the end-capping phenyl group of the hexacenes on the morphology and organic field-effect transistor (OFET) performances. Crystal arrays of the hexacenes were prepared via polydimethylsiloxane (PDMS)-assisted crystallization (PAC) prior to morphological and OFET characterizations. The lattice structures and crystal quality of the hexacenes were evaluated by microscopy and diffraction techniques including single-crystal diffractometer, electron diffraction, and grazing incidence wide-angle X-ray scattering. The systematic analyses led to the following conclusions: (1) the bulkier alkyl side chain assists to form more densely packed crystals with less structural defects; (2) the terminal thiophene rings bring about higher-lying EHOMO, more ordered phase, and crystal orientation, whereas the terminal benzene rings deteriorate the structural order of the active layer and result in the liquid crystal phase; and (3) the phenyl end caps ameliorate the morphological order, intermolecular overlapping, thermal stability and elevate EHOMO. Thus, EH-DTPTt-Ph delivers the highest μh, contributing to high-lying EHOMO, well-oriented crystal array with a longer correlation length, and suitable lattice orientation. This systematic research provides the aspects about the effects of the functionalized S,N-hexacenes on the morphology and OFET characteristics, which is anticipated to be useful for the molecular design of heteroacenes.

Original languageEnglish
Pages (from-to)21756-21765
Number of pages10
JournalACS Applied Materials and Interfaces
Volume11
Issue number24
DOIs
StatePublished - 19 Jun 2019

Keywords

  • GIWAXS
  • S, N-hexacenes
  • chemical modification
  • morphology
  • organic field-effect transistor

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