Synthesis, luminescentand computational analysis of red light emitting Eu (III) organic complexes for OLEDs

Six novel red photoluminscent eight co-ordinate Eu3+ complexes were synthesized by using 6-Chloro-chromone-3-aldehyde as main ligand (L) which are represented as [Eu(L3).X] where X is 2H2O (C1), 1,10-Phenanthroline (C2), Neocuproine (C3), 2,2 '-Bipyridyls (C4), 5,6-Dimethyl-1,10-Phenanthroline (C5), Bathophenanthroline (C6). The above complexes synthesized by solution precipitation method were characterized by elemental analysis, EDAX analyzer to describes the presence of C, H, O, Cl and Eu. Scanning electron microscope (SEM) to indicates semicrystalline nature of complexes, transmission electron microscopy (TEM) to describes size of complexes lies in 55 to 60 nm, nuclear magnetic resonance (1H NMR) and infrared radiation (FTIR) to describe the coordination between Eu3+ ion and ligand and ancillary ligands. Thermo-gravimetric analysis (TGA/DTA) tells that complexes are stable upto 290 degrees C, and photoluminescence (PL) analysis. By using PL data and luminescence decay time (tau), the transition rates, quantum efficiency and the Judd-Ofelt intensity parameters were determined. The luminescence emission spectra for complexes in both states show an intense emission peak (5D0 -> 7F2) at 614 nm (solid) and at 613 nm (solution) of Eu3+ which is responsible to make them an efficient red color emitter in luminescent devices. These complexes are applicable in light emitting devices, traffic signals and home appliances. Percentage branching ratio (beta r) and CIE color coordinates value of all synthesized complexes in both states were analyzed. The value of Percentage branching ratio (beta r) is 79.92-84.65 % in solid state whereas in solution state the value lies in range 49.37-75.37 % and values of percentage branching ratio (beta r) suggests that these complexes are used in lasers and radars systems. The color purity [CP(%)] values are found to be 92.96-94.31 % in solid and 81.24-93.70 % in solution. The band gap is calculated and found to be in the range of 3.7-3.9 eV and used in semiconductor and electroluminescent devices. The complexes (C1-C6) are considered as warm light source because the complexes heaving values of correlated color temperature (CCT) in between 2785 and 3024 K in solid state and 1734 to 2912 K in solution state, which can be efficiently used in LEDs present in hotels, lounges and in many home appliances. The above investigation suggests that synthesized complexes are significant emitters with broad area of utility in laser, electroluminescent materials and display devices.