White-light generation through ultraviolet-emitting diode and white-emitting phosphor

Abstract

White-light-emitting diodes are fabricated by using 375nm emitting InGaN chip with Sr3MgSi2O8:Eu2+ (blue and yellow) or Sr3MgSi2O8:Eu2+, Mn2+ (blue, yellow, and red). At a color temperature of 5892K, the color coordinates are x=0.32, y=0.33, and the color rendering index is 84%; at a color temperature of 4494K, the color coordinates are x=0.35, y=0.33, and the color rendering index is 92%. The blue (470nm) and yellow (570nm) emission bands are originated from Eu2+ ions, while the red (680) emission band is originated from Mn2+ ions in Sr3MgSi2O8 host. The energy transfer among three bands occurs due to the spectral overlap between emission and absorption bands. It is confirmed by the faster decay time of the energy donor. Our white-light-emitting diodes show higher color reproducibility, higher color stability on forward-bias current, and excellent color rendering index in comparison with a commercial YAG:Ce3+-based white-light-emitting diode.