Luminescence Characteristics of Mg2+·Ba2+ Co-Doped Sr2SiO4:Eu Yellow Phosphor for Light Emitting Diodes

Abstract

An improvement for the efficiency of the Sr₂SiO₄:Eu yellow phosphor under the 450~470 ㎚ excitation range have been achieved by dding the co-doping element (Mg2+ and Ba2+) in the host. White LEDs were fabricated through an integration of an blue (InGaN) chip (λm=450 ㎚) and a blend of two phosphors (Mg2+, Ba2+ co-doped Sr₂SiO₄:Eu yellow phosphor+CaS:Eu red phosphor) in a single package. he InGaN-based two phosphor blends (Mg2+, Ba2+ co-doped Sr₂SiO₄:Eu yellow phosphor+CaS:Eu red phosphor) LEDs showed three ands at 450 ㎚, 550 ㎚ and 640 ㎚, respectively. The 450 ㎚ emission band was due to a radiative recombination from an InGaN ctive layer. This 450 ㎚ emission was used as an optical transition of the Mg2+, Ba2+ co-doped Sr₂SiO₄:Eu yellow phosphor and CaS:Eu red hosphor. As a consequence of a preparation of white LEDs using the Mg2+, Ba2+ codoped Sr₂SiO₄:Eu yellow phosphor and CaS:Eu ed phosphor, the highest luminescence efficiency was obtained at the 0.03 mol Ba2+ concentration. At this time, the white LEDs showed he CCT (5300 K), CRI (89.9) and luminous efficacy (17.34 lm/W).