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

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.