Spectral broadening of blue (Sr, Ba)5(PO4)3Cl:Eu2+ phosphors by changing Ba2+/Sr2+ composition ratio for high color rendering index

Abstract A single-phase Sr 5– x – y Ba y (PO 4 ) 3 Cl: x Eu 2+ blue phosphors were synthesized through a solid-state reaction. By increasing Ba 2+ /Sr 2+ ratio, their emission spectra are redshifted (449 nm → 460 nm in main peak) and broadened (34 → 90 nm in half width). Their excitation spectra are in the near ultraviolet region ascribed to be the allowed transition of Eu 2+ from the 4f ground state to the 5d excited state. The phosphors show a similar thermal stability with Y 3 Al 5 O 12 :Ce 3+ commercial phosphor. A white-light-emitting diode was fabricated using 400 nm chip with blue Sr 2.45 Ba 2.45 (PO 4 ) 3 Cl:0.1Eu 2+ and orange Sr 3 SiO 5 :Eu 2+ phosphors. The white-light-emitting diode shows the color coordinates (0.3118, 0.3039) at a white light (correlated color temperature=6810 K) and excellent color rendering index of 86. These results suggest that Sr 2.45 Ba 2.45 (PO 4 ) 3 Cl: 0.1Eu 2+ is a promising blue phosphor for high color-rendering ultraviolet-based white-light-emitting diode.