Enhanced Color Rendering and Color Uniformity of PiG Based WLEDs by Using Red Phosphor Lens

Phosphor-in-glass (PiG) based white light-emitting diodes (WLEDs) are considered as the efficient light source for high-power white lighting due to their highly thermal stability. However, the low color rendering and poor color uniformity limits their actual applications. In this work, a PiG coated with red phosphor lens (PiG-RPL) structure was proposed to enhance the color rendering and color uniformity of WLEDs. The green PiG was prepared by printing and sintering Y 3 Al 3.08 Ga 1.92 O 12 :Ce 3+ (YAGG) phosphor and borosilicate glass powders, and then a red CaAlSiN 3 :Eu 2+ (CASN) phosphor silicone was coated on the green PiG by an inverted dispensing method. Consequently, the PiG-RPL based WLEDs achieve the ultra-high color quality of color rendering index (CRI) values ( \text{R}_{\text {a}} =95.6 and \text{R}_{{9}} =95.2 ) and fidelity/gamut indexes ( \text{R}_{\text {f}} =92 and \text{R}_{\text {g}} =99.2 ) at the current of 350 mA. The PiG-RPL based WLEDs display stable color quality under various currents from 100 to 1000 mA. Furthermore, the color uniformity of PiG-RPL based WLEDs is higher than that of traditional PiG based WLEDs.