We have synthesized a $Eu^{2+}-activated\;Sr_3MgSi_2O_8$ blue phosphor and $(Sr,Ba)_2SiO_4$ yellow phosphor and prepared white LEDs by combining these phosphors with a InGaN UV LED chip. Three distinct emission bands from the InGaN-based LED and the t...
We have synthesized a $Eu^{2+}-activated\;Sr_3MgSi_2O_8$ blue phosphor and $(Sr,Ba)_2SiO_4$ yellow phosphor and prepared white LEDs by combining these phosphors with a InGaN UV LED chip. Three distinct emission bands from the InGaN-based LED and the two phosphors are clearly observed at 405 nm, 460 nm and at around 560 nm, respectively. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This blue emission was used as an optical transition of the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor. The 460 nm and 560 nm emission band is ascribed to a radiative recombination of $Eu^{2+}$ impurity ions in the $Sr_3MgSi_2O_8:Eu$ and $(Sr,Ba)_2SiO_4$ host matrix. As a consequence of a preparation of UV White LED lamp using the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor, the highest luminescence efficiency was obtained at the ration of epoxy/two phosphor (1/0.2361). At this time, the CIE chromaticity was CIE x = 0.3140, CIE y = 0.3201 and CCT (6500 K).