White light-emitting diodes using blue and yellow–orange-emitting phosphors

Abstract

A blue-emitting phosphor, BaMgAl 10O 17:Eu 2+ (BAM) and a yellow–orange phosphor, Ba 2+-codoped Sr 3SiO 5:Eu 2+ were prepared by the solid-state reaction. Excitation and emission spectra results showed that BAM and Ba 2+-codoped Sr 3SiO 5:Eu 2+ can be efficiently excited by near-ultraviolet (n-UV)–visible light from 250 to 440 nm. The effects of the doped-Eu 2+ concentration in BAM and Ba 2+-codoped Sr 3SiO 5:Eu 2+ on the photoluminescence were investigated in detail. White light-emitting diodes (LED) was obtained by combining n-UV LED chip (GaN-based 380 nm emitting) with BaMgAl 10O 17:0.09Eu 2+ and 0.1Ba 2+-codoped Sr 3SiO 5: 0.2Eu 2+ phosphors with the characteristic of color-rendering index of 86, CIE chromaticity coordinates ( x, y) of (0.3216,0.3096), and color temperature T c of 5700 K. As the current increases, the relative intensity simultaneously increases. The CIE chromaticity coordinates ( x, y) of the white LED tends to decrease. The correlated color temperature T c increases from 4100 to 7500 K and the color-rendering index R a increases from 82 to 87 simultaneously.