Organic light-emitting diodes with a nanostructured fulterene layer at the interface between Alq3 and TPD layers

Organic light-emitting diodes (OLEDs) with a nanostructured fullerene (C-60) layer at and near the interface between the electron- and hole-transport layers were fabricated using a vacuum evaporation method. The OLEDs had a fundamental structure of indium-tin-oxide (ITO) anode/copper phtalocyanine (CuPc)/N,N'-dephenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine (TPD)/8-hydroxyquinoline aluminum (Alq(3))/LiF/Al cathode. The electroluminescent (EL) properties have been investigated for the OLEDs with a nanostructured C-60 layer at the TPD/Alq(3) interface and at the different positions in the Alq(3) layer near the TPD/Alq(3) interface. The dependences of the EL properties on the thickness of the inserted C-60 layer and on the position from the interface were examined. The OLEDs with a C-60 monolayer inserted at the TPD/Alq(3) interface showed the highest efficiency.