Study on the influences of quantum well structure on the performance of organic light emitting devices

In this paper, six organic light emitting devices with different quantum well cycles and different position of well structures have been demonstrated. These well structures were composed by N,N′-diphenyl-N,N′-bis(1-napthyl)-1,1′-biphenyl-4,4′-diamine and tris-(8-hydroxyquinoline) aluminum, or tris-(8-hydroxyquinoline) aluminum and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline. The device with one cycles well structure as electron transporting layer exhibits the highest brightness 3354 cd/m2 and current efficiency of 3.46 cd/A. The current efficiency improved owing to carrier confinement and higher exciton formation probability in the well layer. Results illustrated that using proper period of well structure could improve the current efficiency of organic light emitting device and using well structure as electron transporting layer are better than as hole-transporting layer.