UV pumped two color phosphor blend White emitting LEDs

Abstract

We have synthesized an Eu2+-activated Sr3MgSi 2O8 blue phosphor and Ba2SiO4 green phosphor and Ba2+ co-doped Sr3SiO5 red phosphor investigated an attempt to develop white LEDs by combining it with a GaN blue LED chip(λem=405 nm). Three distinct emission bands from the GaN-based LED and the (Sr3MgSi2O8:Eu + Ba 2SiO4:Eu + Ba2+ co-doped Sr3SiO 5:Eu) phosphor are clearly observed at 460nm, 520 nm and at around 600 nm, respectively. These three emission bands combine to give a spectrum that appears white to the naked eye. Our results show that GaN (405 nm chip)-based (Sr3MgSi2O5:Eu + Ba2SiO 4:Eu + Ba2+ co-doped Sr3SiO5:Eu) exhibits a better: luminous efficiency than that of the industrially available product InGaN (460 nm chip)-based YAG:Ce.