Embodiment of the warm white-light-emitting diodes by using a Ba2+ codoped Sr3SiO5:Eu phosphor

Abstract

The shifts of the emission band to longer wavelength (yellow-orange) of the Sr3SiO5:Eu yellow phosphor under the 450–470 nm excitation range have been achieved by adding the codoping element (Ba2+) in the host. In order to apply to white-light-emitting diodes (LEDs) with warm white and high color rendering index, we have fabricated white LEDs through the integration of the InGaN blue LED chip and the two phosphor blends (Sr2SiO4:Eu yellow phosphor +Ba2+ co-doped Sr3SiO5:Eu yellow-orange phosphor) into a single package. By employing two phosphors, covering a red region, the white LEDs show a warm white in the range of 2500–5000 K correlated color temperature and a good color rendering of over 85.