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Solution‐Processible Phosphorescent Blue Dendrimers Based on Biphenyl‐Dendrons and Fac ‐tris(phenyltriazolyl)iridium(III) Cores
Author(s) -
Lo ShihChun,
Bera Raghu N.,
Harding Ruth E.,
Burn Paul L.,
Samuel Ifor D. W.
Publication year - 2008
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200800658
Subject(s) - iridium , phosphorescence , dendrimer , oled , materials science , quantum yield , luminescence , photoluminescence , photochemistry , biphenyl , fluorescence , optoelectronics , polymer chemistry , layer (electronics) , chemistry , nanotechnology , optics , organic chemistry , physics , catalysis
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‐1 H ‐[1,2,4]triazolyl)iridium(III) 1 and fac ‐tris{1‐methyl‐5‐(4‐fluorophenyl)‐3‐ n ‐propyl‐1 H ‐[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.