Investigations into spectroscopic and optoelectronic behaviour of furoic acid-based Eu(III) complexes for advanced photonic applications.

To illuminate the zone of organic light-emitting diodes, a novel series of four red luminescent europium complexes, one binary (C1) and three ternary (C2-C4), of 5-phenyl 2-furoic acid was synthesized with 2,2'-bipyridyl (bipy), bathophenanthroline (batho) and 1,10-phenanthroline (phen) as ancillary ligands and characterized by adopting various analytical techniques. All the findings of energy-dispersive X-ray spectroscopy, elemental (CHN) analysis, Fourier transform infrared, nuclear magnetic resonance, and ultraviolet-visible spectroscopy confirmed the coordination of ligand binding sites with the europium ion. To evaluate the thermal stability, thermogravimetric/difference thermogravimetric measurements were taken that revealed that the synthesized complexes were stable up to 245°C. Diffused reflectance studies indicated that these complexes had potential for their use in wide band-gap semiconductors, as all the four complexes showed metal-centred luminescence as a characteristic red emission peak that was observed at 613 nm under the excitation wavelength of 330 nm. The internal quantum efficiencies and luminescence lifetime of complexes were predicted using Judd-Ofelt and photophysical data. The monoexponential luminescence decay and Judd-Ofelt analysis suggested the presence of a single and asymmetric chemical environment in the coordination sphere of the europium metal. Commission International de l'Eclairage colour coordinates, correlated colour temperature values, and colour purity of the complexes validated their red emission in the visible region.