Several organic electroluminescent devices with different cycle of quantum well structure and different barrier thickness have been demonstrated. The quantum well structures were composed by tris-(8-hydroxyquinoline) aluminum (Alq
3
) and 2
9-dimethyl-4
7-diphenyl-1
10-phenanthroline (BCP). The Alq
3
layer is the potential well of electrons and BCP layer is the potential barrier of electrons. The twice well structure device exhibits the highest current efficiency of 3.46 cd/A
which is about 1.6 times of the conventional three-layers organic light emitting devices. The current efficiency improved owing to carrier confinement and higher exciton formation probability in the well layer (light-emitting layer) when the quantum well period increasing
then the current efficiency would enhanced. But when the quantum well period is too large
the current efficiency will decreased. The devices with different barrier thickness have also been studied in our research
the influence of barrier thickness on current efficiency have been compared. Results illustrated that proper well number and barrier layer thickness can improve the current efficiency of organic light emitting devices.
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