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-Phenylpyridin-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/m2. 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(III) complex to finely tune the emission spectra.