Synthesis and characterization of novel europium β-diketonate organic complexes for solid-state lighting.

Volatile Eu complexes, namely Eu(TTA)3Phen, Eu(x)Y(1-x)(TTA)3Phen; Eu(x)Tb(1-x)(TTA)3Phen; Eu, europium; Y, yttrium; Tb, Terbium; TTA, thenoyltrifluoroacetone; and Phen, 1,10 phenanthroline were synthesized by maintaining stichiometric ratio. Various characterization techniques such as X-ray diffraction (XRD), photoluminescence (PL) and thermo gravimetric analysis/differential thermal analysis (TGA/DTA) were carried out for the synthesized complexes. Diffractograms of all the synthesized complexes showed well-resolved peaks, which revealed that pure and doped organic Eu(3+) complexes were crystalline in nature. Of all the synthesized complexes, Eu0.5Tb0.5(TTA)3Phen showed maximum peak intensity, while the angle of maximum peak intensity for all complexes was almost the same with slightly different d-values. A prominent sharp red emission line was observed at 611 nm when excited with light at 370 nm. It was observed that the intensity of red emissions increased for doped europium complexes Eu(x)Y(1-x)(TTA)3Phen and Eu(x)Tb(1-x)(TTA)3Phen, when compared with Eu complexes. Emission intensity increased in the following order: Eu(TTA)3Phen > Eu0.5Tb0.5(TTA)3Phen > Eu0.4Tb0.6(TTA)3Phen > Eu0.5Y0.5(TTA)3Phen > Eu0.4Y0.6(TTA)3Phen, proving their potential application in organic light-emitting diodes (OLEDs). TGA showed that Eu complexes doped in Y(3+) and Tb(3+) have better thermal stability than pure Eu complex. DTA analysis showed that the melting temperature of Eu(TTA)3Phen was lower than doped Eu complexes. These measurements infer that all complexes were highly stable and could be used as emissive materials for the fabrication of OLEDs.