Emission Band Change of (Sr1-xMx)(3)SiO5:Eu2+ (M=Ca, Ba) Phosphor for White Light Sources Using Blue/Near-Ultraviolet LEDs

Abstract

The luminescence properties of orange-yellow-emitting Eu2+-activated Sr3SiO5 were optimized for application to blue/near ultraviolet (n-UV) light-emitting diodes (LEDs). Sr2.97SiO5:Eu-0.03(2+) showed strong orange-yellow emission peaking at similar to 580 nm under blue and n-UV light of 450 and 405 nm, respectively, and the effects of Ca and Ba substitutions into Sr2+ sites on the emission band change were investigated. For the substitution of Ca, Ca3SiO5:Eu2+ showed no orange-yellow emission under blue light due to the different crystal structures of Ca3SiO5 (monoclinic) and Sr3SiO5 (tetragonal). The redshift and blueshift of the emission band of (Sr1-xBax)(3)SiO5:Eu2+ were explained by the competition between crystal field effect and Nephelauxetic effect. The 460 nm-emitting blue LED-pumped white LED with Sr3SiO5:Eu2+ or a mixture of Sr3SiO5:Eu2+ and green phosphor (Ba2SiO4:Eu2+) were fabricated and they showed color coordinates of (0.343, 0.281) and (0.349, 0.339), respectively.