Novel Eu 2+ -activated thiogallate phosphors for white LED applications: structural and spectroscopic analysis.

Novel Eu 2+ -activated BaGa 2 SiS 6 and Ba 2 Ga 8 SiS 16 thiogallate phosphors were prepared by solid-state reaction route. The BaGa 2 SiS 6 :Eu 2+ phosphor generated a green emission upon excitation at 405 nm, whereas the Ba 2 Ga 8 SiS 16 : x Eu 2+ phosphor could be tuned from cyan to green range with increasing Eu 2+ concentration upon excitation at 365 nm. Additionally, the thermal luminescence properties of the thiogallate phosphors were investigated in the temperature range of 25 to 250 °C. A warm-white LED is fabricated using the combination of a 405 nm blue InGaN-based LED chip with the green-emitting BaGa 2 SiS 6 :0.01Eu 2+ phosphor, and red-emitting Sr 2 Si 5 N 8 :Eu 2+ commercial phosphor with the CRI value of ∼88 and the CCT of 4213 K.