Analysis of fluorescence characteristics of Sm³⁺-doped B₂O₃-rich glasses for Orange-light-emitting diodes

Optical absorption and visible luminescence aspects including visible emission decay times have been examined for six Sm³⁺ (1 mol%)-doped B₂O₃-rich glasses comprising single and mixed alkali oxides which were synthesized via melting-and-quenching approach. Upon intense λ_exci. = 409 nm, fluorescence spectra displayed four bands peaked at 562 nm, 598 nm, 645 nm, and 706 nm owing to ⁴G_5/2 upper level to ⁶H_5/2, ⁶H_7/2, ⁶H_9/2, and ⁶H_11/2 lower levels transitions respectively. Among identified emissions, orange fluorescence (598 nm) is found to be strong in all samples. Moreover Sm³⁺: Li ions having sample exhibits the dominant visible emissions band intensity in all samples, so for this sample, Judd–Ofelt (J[sbnd]O) analysis was carried out to calculate J[sbnd]O parameters Ω_t (t = 2, 4, 6), and from them, radiative transition probabilities, branching ratios (calculated and experimental), and radiative lifetimes of Sm³⁺: ⁴G_5/2 level to distinct lower energy states were derived utilizing absorption and emission spectra. CIE (Commission Internationale de l′éclairage) coordinates, correlated color temperature (CCT), color purity, color rendering index, and luminous efficiency of radiation were determined from visible luminescence spectra of all studied glasses, and obtained CIE coordinates and CCT values lie in the reddish-orange light region of CIE diagram, indicating their potential for orange LEDs (light-emitting diodes) application. Here derived CCT values are lower than the typical warm light sources CCT limit (<3200 K). ⁴G_5/2 state luminescence decay patterns revealed double exponential behavior for assessing the measured lifetimes. Effective bandwidth, stimulated emission cross-section, and gain bandwidth were computed for observed luminescence transitions of Sm³⁺: Li ions possessing sample.