Light emission optimization of europium based complex in multilayer organic light emitting diodes

In this work a detailed study of the electroluminescence of an Organic Light Emitting Diode based on Europium Complex is studied as a function of the emissive layer thickness and growth rate evaporation. The device structure is glass:ITO / TPD [N,N' - bis (3 - methylphenyl) - N,N' - diphenylbenzidine] / Eu(DBM)3phen [tris (dibenzoylmethane) - mono (4,7-dimethylphenantroline) europium (III)] / Alq3 [aluminum - tris (8 - hydroxyquinoline)] / Aluminum. The minimum driving voltage is about 15 Volts although the electrical current is about only 2 mA (wall plug efficiency up to 0.002 %). The electroluminescence spectra and external efficiency are clearly dependent on the Eu (DBM)3phen layer thickness and growth rate evaporation. This results in a strong color change (CIE coordinates). With these results, a model for the device opto-electrical behavior is presented, allowing the device final optimization.

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