Department of Chemistry
Carbazole-based coplanar molecule (CmInF) as a universal host for multi-color electrophosphorescent devices
The synthesis, isomerism, photophysics and electrophosphorescent characterization of some functional cyclometallated iridium(iii) complexes containing 2-[2-(N-phenylcarbazolyl)]pyridine and 2-[3-(N-phenylcarbazolyl)] pyridine molecular frameworks are described. A carbazole-based coplanar molecule (CmInF) obtained through the intramolecular ring closure of aryl substitutions at the C3 and C6 positions exhibits a high triplet energy (ET = 2.77 eV), morphological stability (Tg = 195 °C) and hole mobility in the range of up to 5 × 10-3 cm2 V-1 s-1. Highly efficient multi-color electrophosphorescent devices have been successfully achieved employing CmInF as the universal host material doped with phosphorescent dopants of various colors under the same device configuration of ITO/PEDOT:PSS (300 Å)/TCTA (250 Å)/CmInF: dopant (250 Å)/TAZ (500 Å)/LiF/Al (PEDOT:PSS = poly(ethylene dioxythiophene):polystyrene sulfonate; TCTA = 4,4′,4′′-tri(N- carbazolyl)triphenylamine; TAZ = 3-(4-biphenylyl)-4-phenyl-5-(4-tert- butylphenyl)-1,2,4-triazole). Through the mixing of two phosphorescent dopants of complementary colors, we also fabricated a two-color white organic light-emitting device (WOLED) with the same device structure consisting of 12 wt% FIrpic and 0.3 wt% (Mpg)2Ir(acac) co-doped into CmInF as a single-emitting-layer, which exhibits peak WOLED efficiency of 13.4% (23.4 cd A-1) and 11.2 lm W-1 with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.33, 0.37). In addition, the use of such device structure in full-color OLEDs has the advantages of simplifying manufacturing process and reducing production cost that are the critical issues of commercialization.
Source Publication Title
Journal of Materials Chemistry
Royal Society of Chemistry
Link to Publisher's Edition
Ho, Cheuk-Lam, Liang-Chen Chi, Wen-Yi Hung, Wei-Jiun Chen, Yu-Cheng Lin, Hao Wu, Ejabul Mondal, Gui-Jiang Zhou, Ken-Tsung Wong, and Wai-Yeung Wong. "Carbazole-based coplanar molecule (CmInF) as a universal host for multi-color electrophosphorescent devices." Journal of Materials Chemistry 22.1 (2012): 215-224.