Efficient organic red electroluminescent device with narrow emission peak

We report a red fluorescent material of 3-(dicyanomethylene)-5,5-dimethyl-1(4-dimethylamino-styryl)cyclohexene (DCDDC) and its use as emitter or dopant in tris-(8-hydroxyquinoline) aluminum based electrolumiescent (EL) devices. The DCDDC was synthesized by a simple “one-pot” reaction and shows bright red photoluminescence with a peak wavelength at 650 nm. EL properties of double-layer light-emitting diodes of indium tin oxide (ITO)/poly(N)-vinylcarbazole (PVK):N,N′-diphenyl-N,N-bis(3-methylphenyl)1,1–biphenyl-4,4′-diamine (TPD)/DCDDC/Mg:Ag and ITO/PVK:TPD/DCDDC(1%):Alq3/Mg:Ag using DCDDC as red emitters or dopants were characterized. The device with 1% DCDDC-doped Alq3 as emitting layer has a turn-on voltage of 5 V, and the highest luminance of 5600 cd/m2 is obtained at 15 V. The EL efficiency of the device at 100 cd/m2 is in the range of 1.1 l m/W, and the highest EL efficiency is 1.6 l m/W. The devices emit in the red region, and the full width at half maximum of the EL spectra is 70 nm.