Photoluminescence and white light generation of Dy₂O₃ doped Li₂O-BaO-Gd₂O₃- SiO₂ for white light LED

Dy³⁺-doped Li₂O-BaO-Gd₂O₃-SiO₂ (LBGS) glasses were prepared by traditional melt quenching techniques and characterized through absorption and emission spectra. Tauc's plot for allowed direct and indirect transition are shown studied and observed in the range of 3.5 (eV) to 2.9 (eV). The variation in the band gap with the addition of Dy₂O₃ is due to structural changes in the glass matrix. For 0.5 mol% of Dy³⁺ ions doped LBGS glasses Judd-Ofelt analysis was carried out further these parameters were used to study their radiative properties for the excited luminescent levels of Dy³⁺ ions. White light generation was evaluated as a function of the Dy³⁺ ions concentration by measuring yellow-to-blue emission intensity ratios and CIE chromaticity coordinates. The non-exponential decay were observed for glasses doped beyond 0.1 mol% and were well fitted to IH-model for S = 6 (dipole-dipole interaction). The non-exponential behavior and life time quenching have been accredited to the energy transfer through dipole-dipole interaction among the excited and unexcited Dy³⁺ions. Pulse X-Ray decay time has measured for 0.5 mol% of Dy³⁺ ions doped LBGS glass. CIE-1931 chromaticity coordinates and decay profile analysis were studied. The correlated color temperature (CCT) for LBGS-0.5Dy is found to be 3621 K at λ_exc = 350 nm. The quantum efficiency (η) for the title LBGS-0.5Dy glass is found to be 74%. The highest values for radiative transition probability (A_R), emission cross section (σ(λ_P)), experimental and calculated branching ratio (β_R) have been observed for ⁴F_9/2 → ⁶H_13/2 at 576 nm.