Synthesis and Photophysical Studies of Iridium Complexes Having Different Ligands

概要

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The synthesis and photophysical study of efficient phosphorescent iridium(III) complexes having two different (C∧N) ligands are reported. In order to improve the luminescence efficiency by avoiding triplet–triplet (T–T) annihilation, the iridium complexes, Ir(ppy)2(piq) and Ir(ppy)2(piq-F), are designed and prepared where ppy, piq and piq-F represent 2-phenylpyridine, 1-(phenyl)isoquinoline and 2-(4$'$-fluorophenyl)isoquinoline, respectively. Two ppy ligands and a piq derivative act as a source of energy supply and a piq derivative acts as a chromophore. Since Ir(ppy)3, Ir(piq)3 and Ir(piq-F)3 can be placed in the metal-to-ligand charge transfer (MLCT) excited state, they absorb light effectively. When Ir(ppy)2(piq-F) is placed in excited state, the excitation energy is neither quenched nor deactivated but quickly intramolecular transferred from two ppy ligands to one luminescent piq-F ligand. This can occure because the triplet energy level of ppy is higher than that of piq-F and light is emitted from piq-F ligand in the end. Thus, Ir(ppy)2(piq-F) shows strong photoluminescence originated from piq-F ligand because piq-F ligand is known to have a shorter lifetime than that of ppy ligand. To analyze luminescent mechanism, we calculated these complexes having two different ligand sets theoretically by using computational method.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2006-01-15