title: [The property of white powder LED with different ratio of phosphor].
abstract: White powder light emitting diodes (LED) with different color temperature were made by using different ratio of yellow to orange silicate phosphor. When the ratio of yellow to orange phosphor was less than 7, the peak wavelength of yellow light in spectra was about 570 nm and the wavelength was about 590 nm as the ratio was greater than 7. With the color temperature increasing, the color rendering index and the luminous efficiency increased at the beginning and then decreased. And color temperature of 5 521 K is the optimal value. The reason was the ineffective excitation of blue light due to higher concentration of phosphor and excess red light in spectra. In contrast, blue light was not excited effectively and red light in spectra was little when the color temperature was higher than 5 521 K. The luminous efficiency was decreased, and the decreased magnitude was inconsistency with the testing temperature from 10 to 80 degrees C. This suggests that, besides Auger recombination, the decrease in excitation efficiency of yellow and orange phosphors is different as the temperature rises and orange phosphor's temperature characteristic is superior to that of yellow phosphor.
authors.affiliation: Key Laboratory of Opto-electronics Technology (Beijing University of Technology), Ministry of Education, Beijing 100124, China.
authors.forename: Wei-Ling
authors.initials: WL
authors.lastname: Guo
authors.forename: De-Sheng
authors.initials: DS
authors.lastname: Cui
authors.forename: Bi-Feng
authors.initials: BF
authors.lastname: Cui
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Yan
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu