Fabrication and Characterization of Organic Light-Emitting Diodes Containing Small Molecules Blends as Emissive Layer

Abstract

Organic light-emitting diodes (OLEDs) were fabricated containing guest molecule of Tris (8-hydroxyquinoline) aluminum (Alq3) blend with host molecules of N,N-diphenyl-N,N-bis (3-methylphenyl)-1,1-biphenyl-4,4-diamine (TPD) and 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) small molecules. Optical, photoluminescence (PL) and electroluminescence (EL) properties were investigated with respect to blend systems. The obtained optical energy gap and PL intensity in the blend systems increased due to the transfer of high energy from the host to guest molecules. Luminance and current efficiency were enhanced for blended OLEDs as compared to that of pure Alq3, related to high exiton recombination in guest caused by high injection and accumulation of charge carrier.