FABRICATION AND ELECTROLUMINESCENCE OF DOUBLE-LAYERED ORGANIC LIGHT-EMITTING-DIODES WITH THE AL2O3 AL CATHODE/

The effects of a controlled Al2O3 buffer layer on the behavior of high ly efficient vacuum evaporated aqua-regia-treated indium tin oxide (IT O)/triphenyl diamine (TPD)/8-tris-hydroxyquino-line aluminum Alq(3)/Al 2O3/Al light-emitting diodes are described. It is found that, with a b uffer layer of suitable thickness, both current injection and electrol uminescence output are significantly enhanced. The enhancement is beli eved to be due to increased charge carrier density near the TPD/Alq(3) interface that results from enhanced electron tunneling, and removal of exciton-quenching gap states that are intrinsic to the Alq(3)/Al in terface. (C) 1997 American Institute of Physics.