High-Efficiency Organic Double-Quantum-Well Light-Emitting Devices Using 5,6,11,12-Tetraphenylnaphthacene Sub-monolayer as Potential Well

The double-quantum-well organic light-emitting devices of indium-tin-oxide (ITO)/NPB (50 nm)/rubrene (0.05 nm)/ NPB(4 nm)/rubrene (0.05 nm)/Alq₃ (50 nm)/LiF (0.5 nm)/Al were fabricated, in which N,N-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB) is used as a barrier potential or hole transport layer, tris (8-hydroxyquinoline) aluminum (Alq₃) used as electron transport layer, and 5,6,11,12-tetra\-pheny\-lnaphthacene(rubrene) as a potential well and emitter. The brightness can reach 18610 cd/m² at 13 V. The maximum electroluminescent efficiency of the device was 6.61 cd/A at 7 V, which was higher than that of common dope-type devices. In addition, the electroluminscence efficiency is relatively independent of the drive voltage in the range from 5 to 13 V.