Preparation and Judd-Ofelt Analysis of Warm Red Luminescent Eu3+ Complexes for Semiconductor Lasing Devices.

Six novel red photoluminescent Eu3+ complexes with 3-formyl chromone as the primary sensitizer (L) were synthesized using the solution precipitation method. These complexes are [Eu(L3).X] where X is 2H2O (C1), phen (C2), neo (C3), bipy (C4), dmph (C5), and biquno (C6). These complexes were characterized by elemental analysis, EDAX analysis, SEM, FT-IR, thermo-gravimetric analysis (TGA/DTA) and photoluminescence spectra. The transition rates, quantum efficiency, and J-O intensity parameters were calculated using emission data and luminescence decay time (τ). Complexes exhibit a strong emission peak (5D0 → 7F2) of the Eu3+ ion in their luminescence emission spectra in solid and solution states, making them an effective emitter of the red color in OLEDs. The branching ratio of these complexes ranges from 80.67-82.92 in solid and 50.53-62.65 in solution state; CIE color coordinate of complexes falls in the red region. The color purity ranges [CP(%)] values for solid 95.26-97.27% and for solution ranges 85.11-93.43%. Correlated color temperature (CCT) of the complexes (C1-C6) ranged from 2710 to 3049 K in the solid state and 1775 to 2450 K in the solution state. These complexes are promising red emitters in OLEDs, semiconductors, and leasing devices.

Computational analysis, Urbach energy and Judd-Ofelt parameter of warm Sm3+ complexes having applications in photovoltaic and display devices.

In this work, six reddish orange Sm3+ complexes were synthesized using organic ligand (L) and secondary ligands having hetero atoms by a one-step significant liquid-assisted grinding method and were characterized by spectroscopic techniques. The Urbach energy and band gap energy of the complexes were inspected by a linear fit. Using a least square fitting method, the Judd-Ofelt parameter and radiative properties were also determined. Thermal analysis, colorimetric analysis, luminescence decay time and anti-microbial properties of complexes were studied. The luminescence emission spectra of binary and ternary complexes displayed three characteristic peaks at 565, 603 and 650 nm in the powder form and four peaks at 563, 605, 646 and 703 nm in a solution phase due to 4G5/2 → 6H5/2, 4G5/2 → 6H7/2, 4G5/2 → 6H9/2 and 4G5/2 → 6H11/2 transitions respectively. The most intense transition in the solid phase (4G5/2 → 6H7/2) is accountable for orange color, and in the solution form, the highly luminescent peak (4G5/2 → 6H9/2) is responsible for reddish orange color of Sm3+ complexes. PXRD and SEM analyses suggested that the complexes possess a nanoparticle grain size with crystalline nature. The decent optoelectrical properties of title complexes in the orangish-red visible domain indicated possible applications in the manufacturing of display and optoelectronic devices.