High-triplet-energy dendrons: enhancing the luminescence of deep blue phosphorescent iridium(III) complexes

Lo, Shih-Chun, Harding, Ruth E., Shipley, Christopher P., Stevenson, Stuart G., Burn, Paul L. and Samuel, Ifor D. W. (2009) High-triplet-energy dendrons: enhancing the luminescence of deep blue phosphorescent iridium(III) complexes. Journal of the American Chemical Society, 131 46: 16681-16688. doi:10.1021/ja903157e

Author Lo, Shih-Chun
Harding, Ruth E.
Shipley, Christopher P.
Stevenson, Stuart G.
Burn, Paul L.
Samuel, Ifor D. W.
Title High-triplet-energy dendrons: enhancing the luminescence of deep blue phosphorescent iridium(III) complexes
Journal name Journal of the American Chemical Society   Check publisher's open access policy
ISSN 0002-7863
Publication date 2009-11-25
Sub-type Article (original research)
DOI 10.1021/ja903157e
Volume 131
Issue 46
Start page 16681
End page 16688
Total pages 8
Editor Peter J Stang
Place of publication Washington, D.C., USA
Publisher American Chemical Society
Collection year 2010
Language eng
Subject 03 Chemical Sciences
970102 Expanding Knowledge in the Physical Sciences
970103 Expanding Knowledge in the Chemical Sciences
020499 Condensed Matter Physics not elsewhere classified
030204 Main Group Metal Chemistry
020504 Photonics, Optoelectronics and Optical Communications
020404 Electronic and Magnetic Properties of Condensed Matter; Superconductivity
030503 Organic Chemical Synthesis
030303 Optical Properties of Materials
030301 Chemical Characterisation of Materials
030306 Synthesis of Materials
091208 Organic Semiconductors
Abstract Solution-processable blue phosphorescent emitters with high luminescence efficiency are highly desirable for large-area displays and lighting applications. This report shows that when a fac-tris[1-methyl-5-(4-fluorophenyl)-3-n-propyl-1H-[1,2,4]triazolyl]iridium(III) complex core is encapsulated by rigid high-triplet-energy dendrons, both the physical and photophysical properties can be optimized. The high-triplet-energy and rigid dendrons were composed of twisted biphenyl dendrons with the twisting arising from the use of tetrasubstituted branching phenyl rings. The blue phosphorescent dendrimer was synthesized using a convergent approach and was found to be solution-processable and to possess a high glass transition temperature of 148 °C. The dendrimer had an exceptionally high solution photoluminescence quantum yield (PLQY) of 94%, which was more than three times that of the simple parent core complex (27%). The rigid and high-triplet-energy dendrons were also found to control the intermolecular interactions that lead to the quenching of the luminescence in the solid state, and the film PLQY was found to be 60% with the emission having Commission Internationale de l’Eclairage coordinates of (0.16, 0.16). The results demonstrate that dendronization of simple chromophores can enhance their properties. Single layer neat dendrimer organic light-emitting diodes (OLEDs) had an external quantum efficiency (EQE) of 0.4% at 100 cd/m2. Bilayer devices with an electron transport layer gave improved EQEs of up to 3.9%. Time-resolved luminescence measurements suggest that quenching of triplets by the electron transport layer used in the bilayer OLEDs limits performance.
Q-Index Code C1
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Created: Sun, 13 Dec 2009, 00:03:16 EST