Novel Er-doped organic complexes for application in 1.5 μm emitting solution-processed organic light emitting diodes (OLEDs)

We describe the fabrication and characterization of solution processed organic light emitting diodes (OLEDs) based on novel near-infrared emitting erbium(III) complexes, consisting of three perfluoroalkyl-β-diketone ligands and 5-NO2-1,10-phenanthroline as chelating N,N-donor molecule. The function of N,N molecule is to saturate the coordination sphere of the erbium ion and to harvest excitation light that can be transferred to the excited states of the erbium ion. The devices have been fabricated by spin-coating, using 1 %wt methanol precursor solutions. These Er-complexes form very uniform thin films. The OLED structure is glass/indium–tin oxide(ITO) / poly(3,4-ethylenedioxythiophene) / poly(4styrenesulfonate) (PEDOT:PSS)/Er-complex/Ca/Al. The good electrical response, with low threshold voltages (a few volts), together with the very uniform thin films formed, made these complexes promising for IR emitting displays.