Photoluminescent and electroluminescent properties of 7-(diethylamino)-coumarin-3-carboxylic acid

Blue electroluminescence(EL) from organic light-emitting diodes(OLEDs) with the emitter consisiting of 7-(diethylamino)-coumarin-3-carboxylic acid(DCCA) as dopant and a hole transporting layer 4,4′-bis(9-carbazolyl)biphenyl(CBP) as the host have been investigated.The structure of the devices is indium tin oxide(ITO)/4,4′,4″-tris-N-naphthyl-N-phenylamino-triphenylamine(2-TNATA)(5 nm)/N,N′-bis-(naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine(NPB)(40 nm)/4,4′-bis(9-carbazolyl)biphenyl(CBP)∶DCCA(30 nm)/2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole(Bu-PBD)(30 nm)/LiF(1 nm)/Al(100 nm).The performance of the devices is investigated at different current densities and doping concentrations.The results show that the device with 1% doping concentration has the maximum brightness of 594 cd·m-2 at 12.5 V,and the luminance efficiency of 1.01 cd·A-1 at 20 mA·cm-2.