An Organic Quantum-Well Electroluminescent Device withEnhanced Performance

An organic electroluminescent (EL) device has been constructed with double quantum-well structure consisting of N,N'-bis-(1-naphthl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB) doped with 5,6,11,12-tetraphenylnaphtha- cene (rubrene) as a potential well and emitter, undoped NPB as a barrier potential. The maximum EL efficiency and brightness reach to 5.6cd/A and 40000cd/m², respectively. Most meaningfully, with the increase of the drive voltage, the EL efficiency (cd/A) declines very slowly after reaching its maximum, almost independent of the drive voltage in a wide range from 5 to 13V. The characteristic may be useful in improvement of the lifetime of the device.