Dy³⁺: B₂O₃–Al₂O₃–ZnO–Bi₂O₃–BaO–M₂O (M = Li; Na; and K) glasses: Judd–Ofelt analysis and photoluminescence investigation for WLED applications

Authors aim to study multicomponent barium bismuth borate glasses doped with Dy³⁺ (1 mol%) for white light-emitting diodes (WLEDs) application. All samples, synthesized through melt-quench approach, were characterized by XRD, optical absorption, excitation, emission, and decay lifetimes. Oscillator strengths and Judd–Ofelt intensity parameters (Ω₂, Ω₄, Ω₆) for all glasses were computed from absorption spectra and further, radiative emission transition probability (A_R), branching ratio (β_R), and radiative lifetime (τ_R) were estimated for Dy³⁺ ion various excited states using J–O parameters. Upon 350 nm excitation, ⁴I_15/2 → ⁶H_15/2 [454 nm (blue)], ⁴F_9/2 → ⁶H_15/2 [483 nm (blue)], ⁴F_9/2 → ⁶H_13/2 [575 nm (yellow)], and ⁴F_9/2 → ⁶H_11/2- [663 nm (red)] emission transitions were observed among which ⁴F_9/2 → ⁶H_13/2 transition exhibits the highest intensity. Dy³⁺: Li glass showed relatively higher PL intensity and quantum efficiency than Dy³⁺: Na and Dy³⁺: K samples. Calculated CIE chromaticity (x = ~ 0.35, y = ~ 0.39) coordinates (λ_ex.: 350 nm) and CCTs (4749‒4890 K) proclaimed overall neutral white light emission from all samples, implying their suitability for WLED applications. Decay lifetimes (τ_exp) were determined for Dy³⁺: ⁴F_9/2 → ⁶H_13/2 transition. Additionally, stimulated emission cross-section (σpE) and gain bandwidth (σpE × Δλ_eff) were calculated for respective blue and yellow emission transitions.