Three cationic iridium(III) complexes with 1,10-phenanthroline or compounds containing 1,10-phenanthroline unit as auxiliary ligands: Synthesis and application in polymer light-emitting diodes

摘要

Three yellow-green phosphorescent cationic iridium(III) complexes [(CBT)(2)Ir(phen)]PF6, [(CBT)(2)Ir(BCP)] PF6 and [(CBT)(2)Ir(o-phen)]PF6 were synthesized (phen: 1,10-phenanthroline, BCP: bathocuproine, o-phen: 2-(4-tert-butylpheny1)-5-(4-(1-ethyl-H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)pheny1)-1,3,4-oxadiazole, CBT: 2-(9-(2-ethylhexyl)-9H-carbazol-3-yl)benzo[d]thiazole). All of them were successfully applied in polymer light-emitting diodes: ITO/PEDOT: PSS (40 nm)/PVK: PBD: complex (mass ratios 100: 40: x, x = 1.0, 3.0, and 5.0) (80 nm)/CsF (1.5 nm)/Al (100 nm). The maximum luminances were 8733 cd m(-2), 8878 cd m(-2) and 13019 cd m(-2), the maximum luminance efficiencies were 13.7 cd A(-1), 12.5 cd A(-1) and 17.5 cd A(-1) respectively. Because the steric hindrance of two methyls increase the distance between central Ir3+} and BCP, and the conjugated plane of 1,10-phenanthroline unit in BCP are distorted by two benzene rings, the flow of electrons are partly hindered, [(CBT)(2)Ir(BCP)]PF6 exhibits the lowest electroluminescent performances. Due to the electron-transporting functional group 2,5-dipheny1-1,3,4-oxadiazole and hole-transporting functional group carbazole providing good bipolar property, [(CBT)(2)Ir(o-phen)]PF6 exhibits the best electroluminescent performances. (C) 2016 Elsevier Ltd. All rights reserved.