Highly efficient blue-emitting materials based on 10-naphthylanthracene derivatives for OLEDs

A series of new blue-emitting materials: 2-(10-(naphthalen-2-yl)anthracen-9-yl)pyridine (1); 1-(10-(naphthalen-2-yl)anthracen-9-yl)isoquinoline (2); 9-(3-(10-(naphthalen-2yl)anthracen-9-yl)phenyl)-9H-carbazole (3); 9-(4-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)-9H-carbazole (4); 9-(4-(10-(naphthalen-1-yl)anthracen-9-yl)phenyl)-9H-carbazole (5); 9-(4'-(10-(naphthalen-2-yl)anthracen-9-yl)biphenyl-4-yl)-9H-carbazole (6); and 9-(4'-(10-(naphthalen-1-yl)anthracen-9-yl)biphenyl-4-yl)-9H-carbazole (7) were designed and synthesized via the Suzuki cross-coupling reaction. To explore the electroluminescent properties of these materials, multilayer OLEDs were fabricated in the following sequence: ITO/4,4'-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPB) (50 nm)/blue-emitting materials (1-7) (30 nm)/4,7-diphenyl-1,10-phenanthroline (Bphen) (30 nm)/lithium quinolate (Liq) (2 nm)/Al (100 nm). Among those, a device using 6 as an emitter exhibited a high external quantum efficiency of 3.83% (3.20% at 20 mA/cm(2)) with CIE coordinates of (0.152, 0.114). In order to improve EL efficiency, 1-7 were used as blue host materials for blue dopant materials 4'-[2-(2-diphenylamino-9,9-diethyl-9H-fluoren-7-yl)vinyl]-p-terphenyl (PFVtPh) and 3-(N-phenylcarbazol) vinyl-p-terphenyl (PCVtPh). Using 1 as a host material for blue dopant material PFVtPh, the resultant device showed high EL efficiencies with 10.35 cd/A, 8.77 lm/W, and 5.70% (10.24 cd/A, 6.06 lm/W, and 5.66% at 20 mA/cm(2)). Furthermore, using 4 as a host for the PCVtPh blue dopant, device 4c exhibited efficient deep-blue emissions with a maximum external quantum efficiency of 2.96% and CIE coordinates of (0.154, 0.087), very close to the NTSC blue standard of (0.14, 0.08). (c) 2010 Elsevier B.V. All rights reserved.