Single 395 nm excitation warm WLED with a luminous efficiency of 10486 lm/W and a color rendering index of 907

A blue Sr5(PO4)3Cl:Eu2+ phosphor was synthesized by the solid state reaction method. Higher luminescence intensity was observed by increasing the NH4Cl content to twice the stoichiometric ratio. Then a near UV excited warm white LED was fabricated by using an InGaN/GaN chip (395 nm) coated with tricolor phosphors, including (Sr,Ca)AlSiN3: Eu2+ (red), (Ba,Sr)2SiO4: Eu2+ (green), and Sr5(PO4)3Cl:Eu2+ (blue). Moreover, a two-layer LED fabrication structure was designed to weaken the secondary absorption of blue emission by the red and green phosphors. A good luminescence performance was achieved with the correlated color temperature (CCT) of 3150 K, a color rendering index (CRI) of 90.7, CIE chromatic coordinates of (0.4354, 0.4196), and luminous efficiency of 104.86lm/W.