A broadband-red-emitting phosphor for application in WLEDs with high color rendering index

To address the deficiency of red emission in commercial white light-emitting diodes, a broadband-emitting red phosphor, Ca₂SrAl₂O₆: xEu, was synthesized via a conventional solid-state reaction under a CO atmosphere. Based on the crystal structure of Ca₂SrAl₂O₆, the successful incorporation of Eu ions into the host lattice was confirmed. Under 467 nm blue light excitation, the phosphor exhibited a broad emission band centered at 630 nm with a full width at half maximum of approximately 80 nm. The optimal doping concentration was determined to be x = 0.03, corresponding to an internal quantum efficiency of 41.02%. The phosphor demonstrated good thermal stability, retaining 81.43% of its initial emission intensity at 150 °C, with an activation energy for thermal quenching of 0.2725 eV. To evaluate its practical applicability, a WLED device was fabricated by combining the optimized Ca₂SrAl₂O₆: 0.03Eu phosphor with a 460 nm blue LED chip. The resulting device exhibited a correlated color temperature of 4631 K and a high color rendering index of 92.8, with an R₉ value of 77.4, surpassing that of commercially available white LEDs. Moreover, the device displayed excellent stability under varying operating currents and extended operation. These results demonstrate that the Ca₂SrAl₂O₆: xEu phosphor is a highly promising candidate for advanced solid-state lighting applications.