Improving the current efficiency of organic light-emitting device utilizing the well structure

We have demonstrated efficient organic electroluminescent (EL) devices with well Structure as the emitting layer. The well structure fabricated by alternating deposition of constituent tris-(8-hydroxyquinoline) aluminum (Alq₃) and 4,4-N,N-dicarbazole-biphenyl (CBP) layers improved the current efficiency. The enhanced efficiency can be attributed to the strong accumulation of electrons and holes in the thin Alq₃ layer, which leads to an increase of the exciton formation and exciton recombination probability. The single well device exhibits the highest current efficiency of 4.1 cd/A,which is more than twice than that of the conventional heterostructure device. It is an effective and simple way to improve the efficiency of EL devices by utilizing well structure as the emitting layer with proper well number.