Electroluminescent behaviours of polymer/organic heterostructure devices

Polymer/organic heterostructure electroluminescent devices were fabricated with poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) for emissive polymer layer and various organic materials such as tris(8-hydroxyquinoline) aluminum (Alq3), rubrene (Rub), quinacridone (Qc) and 2-(4′-biphenyl)-5-(4″-tert-butylphenyl)-1,3,4-oxadiazole (PBD) for hole blocking layer. All kinds of organic low molecular materials in this study show hole blocking property, but electroluminescence (EL) characteristics of some structures were not distinctly enhanced because of re-absorption by organic materials, their poor film quality, low electron mobility. The ITO/MEH-PPV/Alq3/Al structured device shows the highest luminescence among the organic molecules used in this study at low current less than about 3 mA.