Effect of Ultrathin Magnesium Layer on the Performance of Organic Light-Emitting Diodes

Organic light-emitting diodes (OLEDs) were fabricated with a structure of indium-tin-oxide (ITO)/polystyrene (PS): N,N’-bis-(3-naphthyl)-N,N’-biphenyl-(1,1’-biphenyl)-4,4’-diamine(NPB)/tris-(8-hydro-xyquinoline)-aluminum(Alq3)/Magnesium(Mg)/tris-(8-hydroxyquinoline)-aluminum(Alq3)/Mg:Ag.By insert- ing an ultrathin Mg layer within an Alq3 layer, the electrical and luminescent properties were optimized. As a result, an optimized film thickness about 5 nm of Mg layer was obtained. By analyzing the optical and electro transporting properties of OLEDs, electron mobility and trap characteristic energy were extracted based on space charge limited conduction (SCLC) and trapped charge limited conduction (TCLC) theories