Optical excitations in star-shaped fluorene molecules

Neil A. Montgomery, Jean-Christophe Denis, Stefan Schumacher, Arvydas Ruseckas, Peter Skabara, Alexander Kanibolotsky, Martin J. Paterson, Ian Galbraith, Graham A. Turnbull, Ifor D. W. Samuel

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Abstract

A detailed study of the low-energy optical transitions in two families of star-shaped molecules is presented. Both families have 3-fold rotational symmetry with oligofluorene arms attached to a central core. In one family, the core of the molecule is a rigid meta-linked truxene, while the other is a meta-linked benzene moiety. The low-energy transitions were studied both experimentally and using time-dependent density functional theory (TD-DFT). The optical transitions of these new star-shaped molecules were compared with corresponding linear oligofluorenes. Both families of star-shaped molecules showed higher absorption and fluorescence dipoles and photoluminescence quantum yields than straight chain oligofluorenes. TD-DFT calculations show that absorption takes place across the entire molecule, and after excited state relaxation, the emission results from a single arm. In both theory and experiment the transition dipole moments show an approximate n0.5 dependence on the number of fluorene units in each arm.
Original languageEnglish
Pages (from-to)2913-2919
Number of pages7
JournalJournal of Physical Chemistry A
Volume115
Issue number14
DOIs
Publication statusPublished - Mar 2011

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Keywords

  • fluorene molecules
  • star-shaped organic semiconductors
  • absorption of light
  • optical excitations

Cite this

Montgomery, N. A., Denis, J-C., Schumacher, S., Ruseckas, A., Skabara, P., Kanibolotsky, A., ... Samuel, I. D. W. (2011). Optical excitations in star-shaped fluorene molecules. Journal of Physical Chemistry A, 115(14), 2913-2919. https://doi.org/10.1021/jp1109042