Multifunctional red phosphorescent bis-cyclometallated iridium complexes based on 2-phenyl-1,2,3- benzotriazole ligand and carbazolyl moieties
Journal
Tetrahedron
Journal Volume
67
Journal Issue
10
Pages
1852-1861
Date Issued
2011-03
Author(s)
Malinauskas, Tadas
Daskeviciene, Maryte
Kazlauskas, Karolis
Su, Hai-Ching
Grazulevicius, Juozas Vidas
Jursenas, Saulius
Wu, Chung-Chih
Getautis, Vytautas
Abstract
Multifunctional phosphorescent bis-cyclometallated iridium(III) complexes based on the 2-phenyl-1,2,3-benzotriazole moiety and bearing branched hole-transporting carbazole fragments were synthesized. The isolated compounds were found to be amorphous and expressed very good solubility. Introduction of flexible aliphatic chains of various lengths into the iridium complexes enabled manipulation of their glass transition temperature. The iridium complexes exhibited red phosphorescence emission at 650 nm with the lifetime of 5.7 μs and phosphorescence quantum yields of 0.22 and 0.17 in solution and solid state, respectively, at room temperature. The shielding effect of the carbazolyl moieties on the concentration quenching of phosphorescence of the iridium centers was found to result in the increased excited state lifetime and quantum yield due to the suppressed exciton migration. Non-optimized OLED devices, based on the phosphorescent bis-cyclometallated iridium(III) complex without host material were fabricated and their electroluminescence properties were evaluated. © 2011 Elsevier Ltd. All rights reserved.
Type
journal article