Sharp green electroluminescence from 1H-pyrazolo[3,4-b]quinoline-based light-emitting diodes

A multilayer organic light-emitting diode was fabricated using a fluorescen t compound {6-N,N-diethylamino-1-methyl-3-phenyl-1H-pyrazolo[3,4-b]quinolin e} (PAQ-NEt2) doped into the hole-transporting layer of NPB {4,4(')-bis[N-( 1-naphthyl-1-)-N-phenyl-amino]-biphenyl}, with the TPBI {2,2',2"-(1,3,5-phe nylene)tris[1-phenyl-1H-benzimidazole]} as an electron-transporting materia l. At 16% PAQ-NEt2 doping concentration, the device gave a sharp, bright, a nd efficient green electroluminescence (EL) peaked at around 530 nm. The fu ll width at half maximum of the EL is 60 nm, which is 60% of the green emis sion from typical NPB/AlQ [where AlQ=tris(8-hydroxyquinoline) aluminum] dev ice. For the same concentration, a maximum luminance of 37 000 cd/m(2) was obtained at 10.0 V and the maximum power, luminescence, and external quantu m efficiencies were obtained 4.2 lm/W, 6.0 cd/A, and 1.6%, respectively, at 5.0 V. (C) 2000 American Institute of Physics. [S0003- 6951(00)01937-9].