Synthetic Manipulation of Excited-state Properties via Alteration of the Heterocyclic Group of 9,9-dimethylfluorene-based-Ir(III) Complexes in Blue PhOLEDs
발표자
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초록
내용
A series of Ir(III) complexes (fac-Ir(py), fac-Ir(pz), fac-/mer-Ir(im), and fac-/mer-Ir(bzim)) with 9,9-dimethylfluorenyl (dmf)-based ligands (dmfC^N or dmfC^C:) tuned with various heterocyclic chelating moieties were prepared and investigated for the development of novel efficient blue phosphorescent dopants. The effect of replacing the phenyl group of the phenylimidazole ligand with a dmf moiety was also investigated. Steady-state photophysical analysis confirmed that the observed emission colors were tunable from λem = 545 nm (fac-Ir(py)) to λem = 462 nm (fac-Ir(bzim)) depending on the heterocycle type. The mer-Ir(im) and fac-/mer-Ir(bzim) with high emission quantum yields of ≥85% in the film state were evaluated as dopant materials in blue PhOLEDs. The mer-Ir(im)- or fac-/mer-Ir(bzim)-doped devices exhibited external quantum efficiencies of 17.3%, 14.2%, and 11.9% with CIE coordinates of (0.21, 0.41), (0.18, 0.33), and (0.19, 0.36), respectively.