Fabrication of red organic light emitting diodes (OLEDs) using EuxY(1-x)(TTA)3Phen organic complexes for solid-state lighting

The mechanism of energy transfer leading to electroluminescence (EL) of a lanthanide complex, EuxY(1-x)(TTA)3Phen (TTA= thenoyltrifluoro-acetone, phen=1,10-phenanthroline), doped into TPBi(1,3,5-tris(N-Phenyl-benzimidizol-2-yl) benzene host at 15 wt% of host is investigated. With the device structure of anode/hole transport layer/EuxY(1-x)(TTA)3Phen (15%): TPBi/electron transport layer/cathode, maximum luminescence of 185.6 cd/m2 and 44.72 cd/m2 was obtained from device I made of Eu0.4Y0.6(TTA)3Phen and device II made of Eu0.5Y0.5(TTA)3Phen, respectively at 18 volts. Saturated red Eu 3+ emission based on 5 D0→ 7 F2 transition is centered at a wavelength of 612 nm with a full width at half maximum of 5 nm. From the analysis of I-V, J-V-L characteristics and electroluminescent (EL) spectra, we conclude that direct trapping of holes and electrons and subsequent formation of the excitation occur on the dopant, leading to high quantum efficiencies at low current densities. These results sho