Judd–Ofelt-enhanced orange-red emission and dual-functional performance of NaBaBi2P3O12:Pr3+ phosphor for solid-state lighting and optical thermometry

Abstract

The pursuit of highly efficient red-emitting phosphors is essential for advancing solid-state lighting and optical sensing technologies. In this study, a novel series of Pr³⁺-doped NaBaBi₂(PO₄)₃ phosphors was successfully synthesized using the conventional solid-state reaction method. Structural analysis using X-ray diffraction (XRD) confirmed the formation of a pure single-phase cubic structure; while scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) revealed the particle morphology and confirmed the elemental composition. Under 445 nm excitation, the phosphor exhibited an intense orange-red emission centered at 602 nm, with an optimal Pr³⁺ doping concentration of 0.01 mol. Judd-Ofelt analysis yielded high intensity parameters, indicating strong electric dipole transitions and a favorable asymmetric coordination environment around the Pr³⁺ ions. The photoluminescence lifetime measurements revealed microsecond-scale decay times, indicating efficient radiative recombination. Chromaticity analysis confirmed emission in the orange-red region, with CIE coordinates of (0.6333, 0.3663) and high color purity of 100 %. Thermal quenching studies demonstrated excellent thermal stability, with the phosphor retaining 75 % of its initial intensity at 423 K. Furthermore, a temperature-dependent decay analysis showed a systematic decrease in lifetime, attributed to thermally activated non-radiative transitions. The relative thermal sensitivity was determined to be 3 × 10⁻² %K⁻¹, underscoring its applicability in optical thermometry. These findings establish NaBaBi₂(PO₄)₃: Pr³⁺ as a promising candidate for high-performance red phosphors in solid-state lighting and optical sensing systems.