Heteroleptic orange light-emitting iridium complexes containing phenylbenzothiazolate ligands

The new heteroleptic orange light-emitting iridium complexes were synthesized and their luminescent properties were investigated. The iridium (III) complexes, Ir(4-Me-2,3-dpq)₂(pbt-R) and Ir(ppy)₂(pbt-R), were prepared, where 4-Me-2,3-dpq, ppy and pbt-R (R=H, F, OMe) represent the ligands of 4-methyl-2,3-diphenylquinoline, 2-phenylpyridine and phenylbenzothiazole derivatives, respectively. The photoabsorption and photoluminescence properties of the iridium complexes were studied, and their band gaps were measured with cyclic voltammetry. The emission maxima of these complexes occurred between 550 and 630 nm with full widths at half maximum (FWHM) of 75–105 nm. The luminescence mechanisms of Ir(4-Me-2,3-dpq)₂(pbt-R) and Ir(ppy)₂(pbt-R) were found to be different, considering their contrasting PL patterns. Owing to their rather large FWHMs, the combination luminescence ranges of these orange phosphorescent complexes with blue phosphorescent Ir(F₂-ppy)₂(pic) were also investigated for the application to the white organic light-emitting diodes.