Abstract

A warm-white light-emitting diode (LED) without blending of different kinds of phosphors is demonstrated. An approach that consists of a blue LED chip and a wavelength-conversion phosphor is carried out. The phosphor is a newly developed yellowish orange CaEuSiAlON ceramic phosphor with high efficiency. The CIE1931 chromaticity coordinates $\left(x,y\right)$ are (0.458, 0.414), the color temperature is 2750 K, and the luminous efficacy of this LED is $25.9 \mathrm{lm}/\mathrm{W}$ at room temperature and with a forward-bias current of 20 mA. The chromaticity of the assembled LED is more thermally stable than that of a LED with a conventional oxide phosphor (YAG:Ce) because of the better thermal stability of the oxynitride phosphor.

© 2004 Optical Society of America