Improvement of the External Quantum Efficiency of Lithium Europium Tungstate and its Application to White Light Emitting Diodes
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概要
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In order to improve the quantum efficiency of the red phosphor LiEu<SUB>0.96</SUB>Sm<SUB>0.04</SUB>W<SUB>2</SUB>O<SUB>8</SUB> under 395 nm excitation, we synthesized samples having various particle sizes. We investigated the emission properties of near UV-pumped white LEDs containing this red phosphor. At room temperature, the external quantum efficiency improved to 49.4 % as the particle size increased, a value comparable to that of commercialized green and blue phosphors used in n-UV LEDs. <BR>In a white LED fabricated by combining an n-UV LED with RGB phosphors, including our synthesized LiEu<SUB>0.96</SUB>Sm<SUB>0.04</SUB>W<SUB>2</SUB>O<SUB>8</SUB>, the luminance of an LED with a red phosphor particle size of 183μm was 1.6 times higher than that with a particle size of 21.7μm. The color rendering properties showed excellent uniformity : there was no observable correlation between color rendering properties and particle size. We consider that an emission peak at 614 nm had a beneficial effect on the luminance and color rendering properties of a white light LED.
- Japan Society of Colour Materialの論文