Photoluminescence‐Based Judd–Ofelt Studies, Quantum Efficiency and DFT Analysis of the Eu 3+ ‐Doped Pb 3 Bi(PO 4 ) 3 Phosphor Prepared by the Combustion Technique for Orange‐Red Solid‐State Lighting Applications

ABSTRACT The Eu 3+ ‐activated Pb 3 Bi(PO 4 ) 3 phosphors were synthesized for the first time by the energy‐efficient combustion technique, and their structural and luminescence properties were investigated for orange‐red solid‐state lighting applications. X‐ray diffraction analysis with Rietveld refinement confirmed the phase‐pure cubic structure (space group I‐43d), while the SEM images revealed a highly porous, agglomerated morphology. Under 394‐nm excitation, the phosphors exhibited characteristic Eu 3+ emissions at 592, 615, 658 and 705 nm, dominated by the hypersensitive 5 D 0 → 7 F 2 electric‐dipole transition at 615 nm. The photoluminescence intensity, asymmetry ratio ( R = 1.418), Judd–Ofelt intensity parameters ( Ω 2 = 2.226 × 10 −20 cm 2 , Ω 4 = 1.849 × 10 −20 cm 2 ), radiative lifetime ( τ R = 3852 μs) and experimental lifetime ( τ = 3592 μs) were found to be optimum at 0.5 mol% Eu 3+ , yielding a quantum efficiency of 93.2%. The main emission's chromaticity coordinates were determined to be high colour purity. The CIE chromaticity coordinates of (0.586, 0.412) and (0.680, 0.319) colour purity of about 97.23% and 97.56% and dominant wavelengths of 592 and 615 nm confirm the nearly saturated orange‐red emission. The DFT‐derived electron‐density map corroborates the Judd–Ofelt parameters. These results establish the combustion‐synthesized Pb 3 Bi(PO 4 ) 3 :Eu 3+ phosphor as a promising candidate for near‐UV‐pumped orange‐red solid‐state lighting.