Tunable emission of polymer light emitting diodes bearing green-emitting Ir(III) complexes: The structural role of 9-((6-(4-fluorophenyl)pyridin-3-yl)methyl)-9H-carbazole ligands

9-((6-Phonylpyridin-3-yl)methyl)-9H-carbazole and 9-((6-(4-fluorophenyl)pyridin-3-yl)methyl)-9H-carbazole were synthesized as ligands by attaching a carbazolyl group to the pyridine in 2-phenylpyridine and 2-(4-fluorophenyl)pyridine, respectively. Four different Ir(III) complexes were prepared using a simple procedure, the solubility of which was significantly greater than that of conventional green-emitting Ir(ppy)(3). Among the many devices fabricated, that which contained 10% of Ir(Cz-ppy)(1)(Cz-Fppy)(2) in PVK/PBD (70:30 wt%), exhibited an external quantum efficiency of 6.80%, luminous efficiency of 20.23 cd/A, and maximum brightness of 17520 cd/m(2). In particular, the electronic property of the new 9-((6-(4-fluorophenyl)pyridin-3-yl)methyl)-9H-carbazole ligand can manipulate the triplet energy level of the Ir(Ill) complex to finely tune the emission spectra. (C) 2009 Elsevier Ltd. All rights reserved.