Synthesis and Characterization of Bis-Orthometalated Ir(III) Complex Consisting of Non-Carbon-Coordinating Ligand

Abstract

We have synthesized a new green emitting bis-orthometalated Ir(III) complex, Ir(mpz)₂hbz, (where mpz is 3-methyl-1-phenyl pyrazole and hbz is the anion of 2′-hydroxy-2-phenylbenzoxazole) and investigated the device performance by doping it in a mixture of PVN (poly-vinylnapthalene) (60 wt%) and PBD (2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole) (40 wt%) or PVK (poly-vinylcarbazole) with 8 wt% doping concentration. The Ir(mpz)₂hbz doped PVN:PBD device demonstrates a better device performance than that of Ir(mpz)₂hbz doped PVK device due to better hole and electron balance in the emissive layer. The maximum external quantum efficiency (η_ext) of 8 wt% Ir(mpz)₂hbz doped PVN:PBD device is ∼1.2% at 12 mA/cm². The maximum brightness is 5,800 cd/m² at 18 V. This work shows that phosphorescent Ir(III) complex which emits the luminescence from the MLCT transition based on a non-carbon-coordinating ligand can comply with the device demand.

Keywords:

• Bis-orthometalated Ir(III) complex
• light-emitting diode
• non-carbon-coordinating ligand
• PVK

Acknowledgments

This work was supported by Korea Ministry of Education, Science and Technology through the Global Partnership Program and APRI-Research Program through a grant provided by Gwangju Institute of Science and Technology.

Notes

†These authors contributed equally to this work.