Open AccessYAG:Ce/(Gd,Y)AG:Ce dual-layered composite structure ceramic phosphors designed for bright white light-emitting diodes with various CCT
Author(s) -
Chen Hu,
Yun Shi,
Xiqi Feng,
Yubai Pan
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.018243
Subject(s) - phosphor , materials science , chromaticity , luminous efficacy , ceramic , luminous flux , transparent ceramics , composite number , light emitting diode , optics , color rendering index , optoelectronics , luminescence , electroluminescence , composite material , layer (electronics) , light source , physics
Y3Al5O12:Ce and (Gd,Y)3Al5O12:Ce ceramic phosphors were fabricated by solid-state reaction method under vacuum sintering. Pure garnet phase of these (Gd,Y)AG:Ce ceramics was confirmed by X-ray diffraction (XRD) with Gd content of 0, 25%, 50% and 75%, respectively. The electroluminescent properties of the unpacked and packed LED devices based on YAG:Ce and (Gd,Y)AG:Ce ceramics were measured. The highest luminous efficacy of 130.5 lm/W was achieved by YAG:Ce ceramic phosphor with thickness of 0.4 mm. However, the correlated color temperature (CCT) of the LED device based on it was high due to a lack of red component in the emission light. Therefore, Y3Al5O12:Ce/(Gdx,Y1-x)3Al5O12:Ce dual-layered composite structure ceramics phosphor were designed and fabricated according to the color space chromaticity diagram. In one demonstration, various CCT could be tuned from 3100 K to 3600 K by these dual-layered structure, while the luminous efficacy can reach 109.9 lm/W. The high luminous efficacy and safe warm white light emitted by these dual-layered phosphors made them promising candidate for white LED devices.