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 ${\mathrm{(PVK):N,N}}^{\mathrm{\prime }}{\mathrm{-diphenyl-N,N-bis(3-methylphenyl)1,1–biphenyl-4,4}}^{\mathrm{\prime }}\mathrm{-diamine}$ (TPD)/DCDDC/Mg:Ag and ${\mathrm{ITO/PVK:TPD/DCDDC(1\%):Alq}}_3/\mathrm{Mg:Ag}$ using DCDDC as red emitters or dopants were characterized. The device with 1% DCDDC-doped ${\mathrm{Alq}}_3$ as emitting layer has a turn-on voltage of 5 V, and the highest luminance of $\text{5600\hspace{0.17em}}{\mathrm{cd/m}}^2$ is obtained at 15 V. The EL efficiency of the device at $\text{100\hspace{0.17em}}{\mathrm{cd/m}}^2$ 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.