Luminescence enhancement and color regulation of Sr2LiAlO4-1.5N : Eu2+ phosphor for high color rendering index white LED applications

The color rendering index (CRI) of white light-emitting diodes (LEDs) is very important for lighting quality. Currently, high-CRI white LEDs are typically fabricated by combining multiple-color phosphors. Therefore, the realization of multipeak-emission phosphors in a single phosphor is valuable. The Sr 2 LiAlO 4 : Eu 2+ phosphor exhibits an obvious double-peak emission in the yellow-green spectral range and has excellent luminescence properties, suggesting its potential application in white LEDs. In this study, a series of Sr 2 LiAlO 4-1.5 x N x : Eu 2+ ( x = 0–0.7) phosphors were successfully synthesized by introducing N 3− ions to replace O 2− ions. The luminescence intensity was significantly enhanced by increasing the N 3− concentration. Upon reaching a concentration of 0.7, the intensity of the yellow emission exceeded that of the green emission, indicating a shift in emission color from green to yellow. The emission peak of the Sr 2 LiAlO 2.95 N 0.7 : Eu 2+ phosphor is at 568 nm, which exhibited broader yellow light emission. Finally, Sr 2 LiAlO 2.95 N 0.7 : Eu 2+ was fabricated with a CaAlSiN 3 : Eu 2+ red phosphor on 450 nm blue LED chips. The fabricated white LEDs was observed to be white light with a high CRI of 92.1 and an adjustable color temperature (4938-6665k), showing its potential application in white LEDs. Sr 2 LiAlO 4 : 0.01Eu 2+ exhibits two distinct emission peaks at 517 and 568 nm. Compared with the undoped N 3− ion Sr 2 LiAlO 4 : 0.01Eu 2+ sample, the 568 nm yellow light emission intensity increased approximately eightfold, while the green light emission intensity quadrupled. The doping of N 3− ions not only markedly increased the emission intensity of the Sr 2 LiAlO 4 : 0.01Eu 2+ phosphor, but also regulated the emission color from green to yellow. • The Sr 2 LiAlO 4-1.5x N x : Eu 2+ phosphors were successfully synthesized by introducing N 3− ions into Sr 2 LiAlO 4 : Eu 2+ phosphor. • The phosphor exhibits double-peak emission in the yellow-green spectral range and show excellent luminescence properties. • By introducing N 3− , the luminescence enhancement of yellow light was significantly higher than that of green light. • The phosphor emission color was regulated from green to yellow and the maximum CRI reached 92.1.