Enhancement of Light Emission from an Europium(III) Complex Based-OLED by Using Layer-By-Layer Assembled Hole-Transport Films

Rare earth complexes hold a promising future in light-emitting devices owing to their strong and sharp luminescence with very high quantum efficiency. Here we report an effective yet very simple way to study and eventually enhance the optoelectronic performance of an organic light emitting device (OLED) based on europium(III) tris(dibenzoylmethane) mono(1,10-phenanthroline), Eu(DBM)3Phen as an emitter. The approach is based on the layer-by-layer deposition of hole-transport films made of PANI/PEDOT:PSS bilayers onto the ITO anode, prior to the emissive layer. As a main advantage, the procedure ensures a great control of the hole-transport film thickness at nanometer level, and thus provides different interfacial conditions. Moreover, we have observed that the devicés current density and luminance are increased when PANI/PEDOT:PSS bilayers are applied. Such OLEDs emit purple color due to contributions from both Eu(III) and PVK emissions.