Novel Eu2+-activated thiogallate phosphors for white LED applications: structural and spectroscopic analysis

Abstract

Novel Eu²⁺-activated BaGa₂SiS₆ and Ba₂Ga₈SiS₁₆ thiogallate phosphors were prepared by solid-state reaction route. The BaGa₂SiS₆:Eu²⁺ phosphor generated a green emission upon excitation at 405 nm, whereas the Ba₂Ga₈SiS₁₆:xEu²⁺ phosphor could be tuned from cyan to green range with increasing Eu²⁺ 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 BaGa₂SiS₆:0.01Eu²⁺ phosphor, and red-emitting Sr₂Si₅N₈:Eu²⁺ commercial phosphor with the CRI value of ∼88 and the CCT of 4213 K.