Solution-Processible Phosphorescent Blue Dendrimers Based on Biphenyl-Dendrons and Fac-tris(phenyltriazolyl)iridium(III) Cores

Authors

  • Shih-Chun Lo,

    Corresponding author
    1. Centre for Organic Photonics and Electronics, School of Molecular and Microbial Sciences The University of Queensland, Chemistry Building, St Lucia, QLD 4072 (Australia)
    • Centre for Organic Photonics and Electronics, School of Molecular and Microbial Sciences The University of Queensland, Chemistry Building, St Lucia, QLD 4072 (Australia).
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  • Raghu N. Bera,

    1. Centre for Organic Semiconductors, SUPA, School of Physics and Astronomy University of St. Andrews, North Haugh, Fife KY16 9SS (UK)
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  • Ruth E. Harding,

    1. Centre for Organic Semiconductors, SUPA, School of Physics and Astronomy University of St. Andrews, North Haugh, Fife KY16 9SS (UK)
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  • Paul L. Burn,

    1. Centre for Organic Photonics and Electronics, School of Molecular and Microbial Sciences The University of Queensland, Chemistry Building, St Lucia, QLD 4072 (Australia)
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  • Ifor D. W. Samuel

    1. Centre for Organic Semiconductors, SUPA, School of Physics and Astronomy University of St. Andrews, North Haugh, Fife KY16 9SS (UK)
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  • We thank CDT Oxford Ltd and EPSRC for financial support. We also thank the EPSRC National Mass Spectroscopy Centre, Swansea, UK. Professor Paul Burn is recipient of an Australian Research Council Federation Fellowship (project number FF0668728).

Abstract

Solution-processible saturated blue phosphorescence is an important goal for organic light-emitting diodes (OLEDs). Fac-tris(5-aryltriazolyl)iridium(III) complexes can emit blue phosphorescence at room temperature. Mono- and doubly dendronized fac-tris(1-methyl-5-phenyl-3-n-propyl-1H-[1,2,4]triazolyl)iridium(III) 1 and fac-tris{1-methyl-5-(4-fluorophenyl)-3-n-propyl-1H-[1,2,4]triazolyl}iridium(III) 4 with first generation biphenyl-based dendrons were prepared. The dendrimers emitted blue light at room temperature and could be solution processed to form thin films. The doubly dendronized 3 had a film photoluminescence quantum yield of 67% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.17, 0.33). OLEDs comprised of a neat film of dendrimer 3 and an electron transport layer achieved a brightness of 142 cd m−2 at 3.8 V with an external quantum efficiency of 7.9%, and CIE coordinates of (0.18, 0.35). Attachment of the fluorine atom to the emissive core had the effect of moving the luminescence to shorter wavelengths but also quenched the luminescence of the mono- and doubly dendronized dendrimers.

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