Dependence of Yellow Phosphor on Optical and Electrical Properties of the White Light Emitting Diode Chip

We prepared the surface mounted white light emitting diode (LED) chips by using yellow phosphors on the blue LED chip. The optical and electrical properties of prepared white LED chips were investigated. The yellow phosphor mixed with transparent epoxy was coated on the prepared LED chip. The optimum mixing conditions with epoxy and yellow phosphor is obtained at the mixing ration of epoxy: yellow phosphor = 97 : 3 wt %. The maximum luminance and light emitting efficiency are above 80,000 cd/m2 and 23.2 lm/W, respectively, at the bias voltage of 2.9 V. There was no distinct change in the luminance strength with changing of the yellow phosphor ratios. The flowing current of the white LED chip is about 30 mA at 2.9 V.

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Effect of outcouping layers on optical and electrical properties of top-emitting organic white light emitting devices

Chinese Journal of Liquid Crystals and Displays ◽

10.3788/yjyxs20153003.0437 ◽

2015 ◽

Vol 30 (3) ◽

pp. 437-443

Author(s):

王光华 WANG Guang-hua ◽

季华夏 JI Hua-xia ◽

张筱丹 ZHANG Xiao-dan ◽

段瑜 DUAN Yu ◽

孙浩 SUN Hao ◽

...

Keyword(s):

Electrical Properties ◽

White Light ◽

Optical And Electrical Properties ◽

Light Emitting ◽

Light Emitting Devices

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Analysis of high-power packages for white-light-emitting diode lamps with remote phosphor

MRS Proceedings ◽

10.1557/proc-0892-ff09-07 ◽

2005 ◽

Vol 892 ◽

Cited By ~ 2

Author(s):

Hong Luo ◽

Jong Kyu Kim ◽

Yangang Xi ◽

E. Fred Schubert ◽

Jaehee Cho ◽

...

Keyword(s):

Ray Tracing ◽

White Light ◽

High Power ◽

Light Emitting Diode ◽

Light Emitting ◽

Yellow Phosphor ◽

Blue Phosphor ◽

Remote Phosphor ◽

Optical Modes ◽

Diffuse Reflector

AbstractAn optimized packaging configuration for high-power white-light-emitting diode (LED) lamps that employs a diffuse reflector cup, a remote phosphor and a hemi-spherically-shaped encapsulation is presented. Ray tracing simulations for this configuration show that the phosphor efficiency can be enhanced by up to 50% over conventional packages. It is experimentally shown that dichromatic LED lamps with remote phosphor and diffuse reflector cup configuration have higher phosphor efficiency by 15.4% for blue-pumped yellow phosphor and by 27% for ultraviolet-pumped blue phosphor over conventional packages. Those improvements are attributed to reduced absorption of the phosphorescence by the LED chip and the reduction of deterministic optical modes trapped inside the encapsulant.

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Screen-Printing of Yellow Phosphor Powder on Blue Light Emitting Diode (LED) Arrays for White Light Illumination

ASME 2007 InterPACK Conference, Volume 1 ◽

10.1115/ipack2007-33971 ◽

2007 ◽

Cited By ~ 11

Author(s):

K. H. Lee ◽

S. W. Ricky Lee

Keyword(s):

White Light ◽

Screen Printing ◽

Light Emitting Diode ◽

Light Illumination ◽

Light Emitting ◽

Yellow Phosphor ◽

Coating Methods ◽

Phosphor Coating ◽

White Light Illumination ◽

Led Arrays

In current technology, white light generation from a light emitting diode (LED) can be achieved by combining the lights from three fundamental colors, namely, red, green and blue (RGB), of LEDs or by coating a phosphor layer onto the surface of a LED chip. The first method involving the RGB color mixing technique requires a complicated electrical circuit design for the control of light intensity and uniformity on the three different colors of LEDs and hence increases the costs of manufacturing. The second method is implemented by coating a layer of yellow phosphor on a blue LED chip for white light illumination. The quality of generated white light heavily depends on the packing density, the thickness and the uniformity of the phosphor coating. There have been some coating methods available in the industry. Each one of them has its own pros-n-cons. In the present study, a new yellow phosphor coating method by screen-printing on blue LED arrays is developed. Compared with conventional coating methods, this screen-printing method is considered relatively simple and rather effective. The newly developed method and the results of prototyping are introduced in this paper in detail.

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Luminescence Property of Eu2+ Doped Strontium Silicate Yellow Phosphor for White Light Emitting Diode

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.368-372.363 ◽

2008 ◽

Vol 368-372 ◽

pp. 363-365

Author(s):

Hong He ◽

Ren Li Fu ◽

Xiu Feng Song ◽

De Liu Wang

Keyword(s):

White Light ◽

Luminescence Property ◽

Light Emitting Diode ◽

Broad Emission Band ◽

Conventional Solid State Reaction ◽

Weak Band ◽

Yellow Colour ◽

Light Emitting ◽

Yellow Phosphor ◽

Strontium Silicate

Eu2+ activated strontium silicate (Sr3SiO5:Eu2+) yellow phosphor was prepared by the conventional solid-state reaction technique in reduction atmosphere with starting materials SrCO3, SiO2 and Eu2O3. The phase, morphology and luminescence property of the samples were analyzed. The X-ray diffraction analysis showed the main phase in all samples is tetragonal Sr3SiO5. With Eu2+ ions doped into the host lattice, the Sr3SiO5:Eu2+ phosphors absorb light energy in the UV-visible spectrum region and show an intense broad emission band in the yellow colour range (around 570 nm) and a weak band in the blue region (around 470 nm). The excitation and the emission bands are originated from the 4f−5d transition of Eu2+ ions. When the concentration of Eu2+ ions increases, the emission peaks of phosphors shift to longer wavelengths. The effective emission in the yellow colour indicates that phosphor as potential candidates for white light-emitting-diodes.

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