Fluorenyl-substituted silole molecules: Geometric, electronic, optical, and device properties

Xiaowei Zhan, Andreas Haldi, Chad Risko, Calvin K. Chan, Wei Zhao, Tatiana V. Timofeeva, Aleksander Korlyukov, Mikhail Yu Antipin, Sarah Montgomery, Evans Thompson, Zesheng An, Benoit Domercq, Stephen Barlow, Antoine Kahn, Bernard Kippelen, Jean Luc Brédas, Seth R. Marder

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

A series of silole molecules with fluorenyl substituents at varying positions - 1-(9,9-dimethylfluoren-2-yl)-1,2,3,4,5-pentaphenylsilole, 1-(fluoren-9-yl)-1,2,3,4,5-pentaphenylsilole, 1,1,3,4-tetraphenyl-2,5-bis(9,9- dimethylfluoren-2-yl)silole, and 1,1-diphenyl-2,3,4,5-tetrakis(9,9- dimethylfluoren-2-yl)silole - has been synthesized and compared to the previously reported compounds, 1,1,2,3,4,5-hexaphenylsilole and 1,1-bis(9,9-dimethylfluoren-2-yl)-2,3,4,5-tetraphenylsilole. The effect of fluorenyl substitution pattern on the geometric, thermal, electronic, optical, and electroluminescence properties was investigated both experimentally and theoretically. Analysis of the X-ray crystal packing diagrams for two new fluorenyl-substituted siloles indicates the presence of π-π stacking and CH⋯π interactions in the solid state. Across the series, excellent thermal and morphological stabilities are displayed. Photoelectron/inverse- photoelectron spectroscopy measurements and density functional theory (DFT) calculations suggest that increased conjugation length through substitution at the 2- and 5-positions plays a more significant role in tuning the ionization potentials and electron affinities of these siloles than do inductive effects through substitution of the silicon. The electronic structure (e.g., HOMO-LUMO gap) and, hence, the optical absorption and fluorescence properties are also sensitive to the positions at which the fluorenyl groups are introduced, with substitution at the 2,5-positions having the largest effect. Solution-processed electroluminescent devices fabricated with the fluorenyl-substituted siloles as the emissive layer have luminous efficiencies as high as 3.6 cd A-1.

Original languageEnglish (US)
Pages (from-to)3157-3166
Number of pages10
JournalJournal of Materials Chemistry
Volume18
Issue number26
DOIs
StatePublished - 2008

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Chemistry

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    Zhan, X., Haldi, A., Risko, C., Chan, C. K., Zhao, W., Timofeeva, T. V., Korlyukov, A., Antipin, M. Y., Montgomery, S., Thompson, E., An, Z., Domercq, B., Barlow, S., Kahn, A., Kippelen, B., Brédas, J. L., & Marder, S. R. (2008). Fluorenyl-substituted silole molecules: Geometric, electronic, optical, and device properties. Journal of Materials Chemistry, 18(26), 3157-3166. https://doi.org/10.1039/b803470b