Syntheses and application of novel blue phosphorescent iridium complexes to OLEDs

We synthesized novel iridium complexes having a cyano and/or fluorine-containing phenylpyridine ligands for organic light emitting diodes (OLEDs). The optical properties of these complexes were investigated by ultraviolet-visible (UV-vis) absorption and photoluminescence (PL) spectrophotometer. The emission color ranges from blue to green depending on the position of substituent groups. One of the complexes, bis[(5-cyano-2-fluorophenyl)-pyridinato-N, C-2] (dipivaloyinate) iridium (III), with the substituent groups on 2 and 5 positions, showed a greenish blue emission peak at 476 nm. The OLED with a structure of glass substrate / indium-tin-oxide (ITO) / tetraphenyl-benzidine-containing poly (arylene ether sulfone) (TPDPES) doped with tris (4-bromophenyl) aminium hexachloro-antimonate (TBPAH) / 2,2'-Bis[3-(N, N'-ditolviamino) phenyl]biphenyl (3DTAPBP) / iridium complex-doped 2,2'-Bis[4-(N-carbazole)phenyl] biphenyl (4CzPBP) / 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (t-Bu-TAZ) / lithium fluoride (LiF)/aluminum (Al) exhibited the external quantum efficiency of 17% and the power efficiency of 33 lm/W at 100cd/m(2).