Novel near-UV-excitable Eu3+ doped K3Ca2(SO4)3× (X = F, Cl, Br) halosulphate phosphors for white LEDs

Narrow-band red inorganic phosphors excited by near-ultraviolet (n-UV) light have significant application potential in the manufacture of white light-emitting diodes (LEDs) with high R9 index. Novel near-UV-excitable Eu 3+ doped K 3 Ca 2 (SO 4 ) 3 × (X = F, Cl, Br) halosulphate phosphors were synthesized via high-temperature solid-state reaction method. By modifying the non-activating ions in the host matrix, the luminescence properties of Eu 3+ were effectively enhanced across various matrices, thereby optimizing the performance of this series of phosphors. As-prepared phosphors can be activated under 397 nm excitation and emit red light at 619 nm, corresponding to 5 D 0  →  7 F 2 transitions of Eu 3+ . Optimization of the doping concentration revealed that the optimal Eu 3+ concentration for different host matrices is 0.13. Notably, the K 3 Ca 2 (SO 4 ) 3 F host matrix doped with Eu 3+ exhibits stronger emission intensity and better performance. The K 3 Ca 2 (SO 4 ) 3 F:0.13Eu 3+ phosphor exhibited long fluorescence lifetime of 0.42 ms and high color purity of 92.25 %. The emission intensity of K 3 Ca 2 (SO 4 ) 3 F:0.13Eu 3+ at 423 K can retain 89.5 % of its value at room temperature. A white LEDs device was fabricated by mixing and encapsulating K 3 Ca 2 (SO 4 ) 3 F:0.13Eu 3+ phosphor with commercial BaMgAl 10 O 17 :Eu 2+ blue and (Ba, Sr) 2 SiO 4 :Eu 2+ green phosphors onto 397 nm n-UV InGaN chip. The device emits bright white light and exhibits high color rendering index (Ra = 79.9, R9 = 86.5) and a suitable correlated color temperature (CCT = 5915 K) at 50 mA drive current. The results suggest that this work provides new assistance in achieving high color rendering white LEDs excited by n-UV light.