Color tuning of iridium complexes for organic light-emitting diodes: The electronegative effect and π-conjugation effect
摘要:
Novel red phosphorescent emitter bis(4-phenylquinazolinato-N,C-2') iridium(acetylacetonate) [(pqz)(2)Ir(acac)], bis(1-(1'-naphthyl)-5-methylisoquinolinato-N,C-2')iridium(acetylacetonate) [(1-mniq)(2)Ir(acac)] and bis(1-(2'-naphthyl)-5-methylisoquinolinato-N,C-2')iridium(acetylacetonate) [(2-mniq)(2)Ir(acac)] have been synthesized and fully characterized. The electronegative effect of (pqz)(2)Ir(acac) ligand shows almost the same influence as the extended pi-conjugation effect of (2-mniq)(2)Ir(acac). Density functional theory (DFT) was applied to calculate the Kohn-Sham orbitals of HOMOs and LUMOs in the iridium complexes to illustrate the N(1) electronegative atom effect. Finally, lowest triplet state (T-1) energies calculated by time-dependent DFT (TDDFT) were compared with the experimental electroluminescent data. The calculated data for the iridium complexes agreed fairly well with experimental data. Electroluminescent devices with a configuration of ITO/NPB/CBP:dopant/BCP/AlQ(3)/LiF/Al were fabricated. The device using (pqz)(2)Ir(acac) as a dopant showed deep-red emission with 1931 CIE (Commission International de L'Eclairage) chromaticity coordinates x = 0.70, y = 0.30. (c) 2006 Elsevier B.V. All rights reserved.