Organic Light Emitting Diodes with a Nanostructured Fullerene Layer at the Interface between Alq3 and TPD Layers

Abstract

Organic light-emitting diodes (OLEDs) with a nanostructured fullerene (C60) 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 (Alq3)/LiF/Al cathode. The electroluminescent (EL) properties have been investigated for the OLEDs with a nanostructured C60 layer at the TPD/Alq3 interface and at the different positions in the Alq3 layer near the TPD/Alq3 interface. The dependences of the EL properties on the thickness of the inserted C60 layer and on the position from the interface were examined. The OLEDs with a C60 monolayer inserted at the TPD/Alq3 interface showed the highest efficiency.