title: Rational design, synthesis, and characterization of deep blue phosphorescent Ir(III) complexes containing (4'-substituted-2'-pyridyl)-1,2,4-triazole ancillary ligands.
abstract: On the basis of the results of frontier orbital considerations, 4-substituted-2'-pyridyltriazoles were designed to serve as ancillary ligands in 2-phenylpyridine main ligand containing heteroleptic iridium(III) complexes that display deep blue phosphorescence emission. The iridium(III) complexes, Ir1-Ir7, prepared using the new ancillary ligands, were found to display structured, highly quantum efficient (Φp = 0.20-0.42) phosphorescence with emission maxima in the blue to deep blue 448-456 nm at room temperature. In accord with predictions based on frontier orbital considerations, the complexes were observed to have emission properties that are dependent on the electronic nature of substituents at the C-4 position of the pyridine moiety of the ancillary ligand. Importantly, placement of an electron-donating methyl group at C-4' of the pyridine ring of the 5-(pyridine-2'-yl)-3-trifluoromethyl-1,2,4-triazole ancillary ligand leads to an iridium(III) complex that displays a deep blue phosphorescence emission maximum at 448 nm in both the liquid and film states at room temperature. Finally, an OLED device, constructed using an Ir-complex containing the optimized ancillary ligand as the dopant, was found to emit deep blue color with a CIE of 0.15, 0.18, which is close to the perfect goal of 0.15, 0.15.
authors.affiliation: Department of Chemistry, Pusan National University, Busan 609-735, Korea.
authors.forename: Hea Jung
authors.initials: HJ
authors.lastname: Park
authors.forename: Ji Na
authors.initials: JN
authors.lastname: Kim
authors.forename: Hyun-Ji
authors.initials: HJ
authors.lastname: Yoo
authors.forename: Kyung-Ryang
authors.initials: KR
authors.lastname: Wee
authors.forename: Sang Ook
authors.initials: SO
authors.lastname: Kang
authors.forename: Dae Won
authors.initials: DW
authors.lastname: Cho
authors.forename: Ung Chan
authors.initials: UC
authors.lastname: Yoon
mesh_terms: D018360:Crystallography, X-Ray; D007495:Iridium / Q000737:chemistry*; D008024:Ligands; D049408:Luminescent Agents / Q000138:chemical synthesis* / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D014230:Triazoles / Q000737:chemistry*
chemical_list: D008024:Ligands; D049408:Luminescent Agents; D009942:Organometallic Compounds; D014230:Triazoles; C045575:1,2,4-triazole; D007495:Iridium