LUMINESCENT PROPERTIES OF Sr3B2O6: Eu2+ YELLOW-EMITTING PHOSPHOR FOR WHITE LIGHT-EMITTING DIODES

2013 ◽  
Vol 06 (01) ◽  
pp. 1350009 ◽  
Author(s):  
QUAN-SHENG LIU ◽  
TIAN CUI ◽  
XI-YAN ZHANG ◽  
YUE SONG
Keyword(s):  
Wide Band ◽  
Luminescent Properties ◽  
Color Temperature ◽  
Broad Emission Band ◽  
Band Spectrum ◽  
White Led ◽  
Solid State Method ◽  
Light Emitting ◽  
Yellow Phosphor ◽  
Cie Chromaticity

Eu2+ doped Sr3B2O6 yellow phosphor for warm white LED was synthesized by high temperature solid-state method. The structure and optical properties of Sr3B2O6 : Eu2+ were studied. Results indicate that Sr3B2O6 : Eu2+ has a rhombohedral crystalline structure. The excitation spectrum of phosphor is a wide-band spectrum mainly peaking at 469 nm, which is suitable for GaN -based blue light LED excitation. The luminescent spectrum of phosphor exhibits a broad emission band centered at 566 nm, corresponding to the typical 4f65d1–4f7 transition of Eu2+ . Guass fitting shows the main emission peak is at 575 nm, which is identical with the dominant wavelength of the yellow phosphor. The CIE chromaticity coordinate of white LED is (x = 0.389, y = 0.419). The LED reveals warm tone and the relevant color temperature of that is 4044 K. The luminescent efficiency of White LED reaches 18l m/W, which is higher than reported.

scholarly journals New Multicolor Tungstate-Molybdate Microphosphors as an Alternative to LED Components

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6608
Author(s):  
Justyna Czajka ◽  
Agata Szczeszak ◽  
Nina Kaczorowska ◽  
Stefan Lis
Keyword(s):  
Color Change ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Luminescence Spectroscopy ◽  
Solid State Method ◽  
Light Emitting ◽  
Tetragonal Crystal ◽  
Emission Color ◽  
The Matrix ◽  
Cie Chromaticity

Due to the ongoing need to create phosphors with the appropriate emission color for the production of light emitting diodes, we decided to synthesize a series of multicolour microphosphors with tunable visible emissions, depending on the composition of dopant ions. In this work, we investigated the structure, morphology, and luminescent properties of new molybdate–tungstate phosphors co-doped with Tb3+ and Eu3+ ions. The conventional high temperature solid state method was used to prepare a series of CaMoyW1−yO4:Eu3+x/Tb3+1−x materials. In order to obtain phosphors with the most promising luminescent properties, the experiment was planned by taking into account the different composition of the matrix and the concentration of the particular dopant ions (Eu3+x/Tb3+1−x, x = 0.001, 0.003, 0.005, 0.007, 0.009). As a result, luminescent materials were obtained with a pure tetragonal crystal structure, the space group of I41/a, confirmed by X-ray diffraction (XRD). The size and shape of the particles obtained from the materials were analyzed based on scanning electron microscopy images. Luminescence spectroscopy (excitation and emission spectra, decay lifetimes) was utilized to characterize the luminescence properties of the as-prepared phosphors. The color change of the emission from green-yellow to orange-red was confirmed using the 1931 Comission Internationale de l’Eclairage (CIE) chromaticity coordinates and color correlated temperature (CCT).

A Study on Orthogonal Experiments of YAG: Ce3+ Yellow Phosphor for White LED

2011 ◽  
Vol 216 ◽  
pp. 383-387 ◽  
Author(s):  
Rong Feng Guan ◽  
Qin Qin Li ◽  
Shuai Mou Li
Keyword(s):  
Orthogonal Experiment ◽  
Luminescent Properties ◽  
Precipitation Method ◽  
Prepared Phosphor ◽  
Luminescent Materials ◽  
White Led ◽  
Yellow Phosphor ◽  
Sintering Time ◽  
Orthogonal Experiments ◽  
Co Precipitation

The YAG yellow phosphor was synthesized by Co-precipitation Method and its luminescent properties were characterized. The Orthogonal Experiment results that under laboratory conditions, the prepared phosphor luminous intensity reached at the maximum and the optical properties of compound as white up to the best with blue-chip, when calcinations temperature up to 1600°C, sintering time is 3h, the Ce3+content is 0.05.Therefore, the phosphor could provide a theoretical basis for the design and development of white LED with luminescent materials, promoting the practical of white LED.

scholarly journals Preparation of Bismuth Oxide Photocatalyst and Its Application in White-light LEDs

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Yen-Chang Chu ◽  
Gang-Juan Lee ◽  
Chin-Yi Chen ◽  
Shih-Hsin Ma ◽  
Jerry J. Wu ◽  
...  
Keyword(s):  
Bismuth Oxide ◽  
White Light ◽  
Front Surface ◽  
Color Temperature ◽  
Spray Pyrolysis Method ◽  
Light Emitting ◽  
White Leds ◽  
Air Purifier ◽  
Cie Chromaticity ◽  
White Light Emitting Diodes

Bismuth oxide photocatalysts were synthesized and coated on the front surface of phosphor-converted white light-emitting diodes to produce a safe and environmentally benign lighting source. Bismuth oxide photocatalyst powders were synthesized with a spray pyrolysis method at 500°C, 600°C, 700°C, and 800°C. Using the absorption spectrum in the blue and UV regions of the bismuth oxide photocatalysts, the blue light and UV leakage problems of phosphor-converted white LEDs can be significantly reduced. The experimental results showed that bismuth oxide photocatalyst synthesized at 700°C exhibited the most superior spectrum inhibiting ability. The suppressed ratio reached 52.33% in the blue and UV regions from 360 to 420 nm. Related colorimetric parameters and the photocatalyst decomposition ability of fabricated white-light LEDs were tested. The CIE chromaticity coordinates(x,y)were (0.349, 0.393), and the correlated color temperature was 4991 K. In addition, the coating layer of photocatalyst can act as an air purifier and diffuser to reduce glare. A value of66.2±0.60 ppmv of molecular formaldehyde gas can be decomposed in 120 mins.

scholarly journals High Efficiency and Color Rendering Quantum Dots White Light Emitting Diodes Optimized by Luminescent Microspheres Incorporating

Nanophotonics ◽  
2016 ◽  
Vol 5 (4) ◽  
pp. 565-572 ◽  
Author(s):  
Wei Chen ◽  
Kai Wang ◽  
Junjie Hao ◽  
Dan Wu ◽  
Jing Qin ◽  
...  
Keyword(s):  
Quantum Dots ◽  
White Light ◽  
High Efficiency ◽  
Lattice Structure ◽  
Light Emitting Diode ◽  
Luminescent Properties ◽  
Color Temperature ◽  
High Quantum Efficiency ◽  
Light Emitting ◽  
Color Rendering

AbstractIn this research, we have developed an approach by incorporating quantum dots (QDs) with red emission into mesoporous silica microspheres through a non-chemical process and obtained luminescent microspheres (LMS). Owing to the lattice structure of LMS, QDs were effectively protected from intrinsic aggregation in matrix and surface deterioration by encapsulant, oxygen and moisture. The LMS composite has therefore maintained large extent luminescent properties of QDs, espe-cially for the high quantum efficiency. Moreover, the fabricated white light emitting diode (WLED) utilizing LMS and YAG:Ce yellow phosphor has demonstrated excellent light performance with color coordinates around (x = 0.33, y = 0.33), correlated color temperature between 5100 and 5500 K and color rendering index of Ra = 90, R9 = 95. The luminous efficiency of the WLED has reached up to a new record of 142.5 lm/W at 20 mA. LMS provide a promising way to practically apply QDs in lightings and displays with high efficiency as well as high stability.

High color rendering index single phase white light emitting phosphors based on Tb3+/Sm3+ co-doped CePO4 nanocrystals: the role of Tb3+ as a bridge between Ce3+ and Sm3+

2019 ◽  
Vol 43 (44) ◽  
pp. 17367-17382 ◽  
Author(s):  
Sisira S. ◽  
Linju Ann Jacob ◽  
Kamal P. Mani ◽  
Biju P. R. ◽  
N. V. Unnikrishnan ◽  
...  
Keyword(s):  
White Light ◽  
Single Phase ◽  
Color Temperature ◽  
Light Emitting ◽  
Chromaticity Coordinates ◽  
Color Rendering Index ◽  
Cie Chromaticity ◽  
Color Rendering

Single phase white light emitting CePO4 nanocrystals doped with Tb3+ and Sm3+ were synthesized. The quality of white light is characterized by CIE chromaticity coordinates, color temperature, color rendering index and quantum yield.

Synthesis and Luminescent Properties of Blue-Emitting Hydrotalcite-Like Compound for NUV Light-Emitting Diodes

2014 ◽  
Vol 1004-1005 ◽  
pp. 340-343
Author(s):  
Chen Hong ◽  
Hui Gao ◽  
Zhao Xuan ◽  
Li Hong Jiang ◽  
Qi Dan Ling
Keyword(s):  
Fluorescence Spectrum ◽  
Blue Light ◽  
Light Emitting Diodes ◽  
Luminescent Properties ◽  
Coprecipitation Method ◽  
White Led ◽  
Hybrid Nanocomposite ◽  
Inorganic Hybrid ◽  
Light Emitting ◽  
Bright Blue

Layered organic-inorganic hybrid nanocomposite material with the hydrotalcite-like structure, containing Mg (II),Zn (II) and Al (III) in the layers, and salicylate ions in the interlayer, have been prepared by a simple coprecipitation method (MgAlZn-sal-HTlc). Fluorescence spectrum, XRD and TG were used to characterize the properties of the sample. Additionally, A LED device was fabricated by coating MgAlZn-sal-HTlc onto InGaN-based LED chip. The device emits bright blue light. All the results indicate that blue-emitting fluorescent hydrotalcite-like compound can act as blue components in the fabrication of white LED.

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

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.

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

2006 ◽  
Vol 510-511 ◽  
pp. 106-109 ◽  
Author(s):  
Chang Sik Son ◽  
Ho Jung Chang ◽  
Kang Hyun Jaekal ◽  
Young Chol Chang ◽  
Soo Wohn Lee
Keyword(s):  
Electrical Properties ◽  
Bias Voltage ◽  
White Light ◽  
Light Emitting Diode ◽  
White Led ◽  
Optical And Electrical Properties ◽  
Maximum Luminance ◽  
Mixing Conditions ◽  
Light Emitting ◽  
Yellow Phosphor

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.

Luminescence properties of single-phase color-tunable Li4SrCa(Si2O4N8/3):Eu2+ phosphor for white light-emitting diodes

RSC Advances ◽  
2016 ◽  
Vol 6 (45) ◽  
pp. 38731-38740 ◽  
Author(s):  
Chenxia Li ◽  
Jian Dai ◽  
Hua Yu ◽  
Degang Deng ◽  
Jun Huang ◽  
...  
Keyword(s):  
White Light ◽  
Single Phase ◽  
Light Emitting Diodes ◽  
Color Temperature ◽  
White Led ◽  
Light Emitting ◽  
Color Coordinates ◽  
Uv Led ◽  
Color Tunable ◽  
White Light Emitting Diodes

A white LED consisting of a LSCSN:0.03Eu2+ phosphor and a 375 nm UV LED chip had CIE color coordinates of (0.3568, 0.3111) and achieved a Ra of 82.5 around the correlated color temperature of 3318 K.

Synthesis and Optical Characterization of M-α-Sialon (M=Ca, Ba, Sr) Doped by Europium

2014 ◽  
Vol 90 ◽  
pp. 141-148
Author(s):  
Daniel Michalik ◽  
Tomasz Pawlik ◽  
Malgorzata Sopicka-Lizer ◽  
Radosław Lisiecki
Keyword(s):  
Chemical Resistance ◽  
Solid State Reaction Method ◽  
Rare Earth Ions ◽  
Color Temperature ◽  
Broad Emission Band ◽  
White Led ◽  
Photoluminescence Properties ◽  
Synthesis Parameters ◽  
Broad Emission

Oxynitrides compounds are interesting for white LED industry because more covalent matrix's bonds in comparison to oxides enable to obtain higher color temperature of wLED. The Sialon's luminescence material doped by rare earth ions with high mechanical and chemical resistance and a broad emission band may become an alternative for garnet phosphors. The goal of the study was to investigate influence of divalent stabilizing cations on luminescence properties of M-α-Sialon doped with Eu2+in order to estimate its potential for YAG:Ce replacement in WLEDs. The compound of general formula EuxM1-xSi9,6Al2,4O0,8N15,2, where M=Ca, Ba, Sr, was prepared by the solid state reaction method from the mixture of the relevant oxides, nitrides and carbonates. Synthesis was carried out at the temperature of 1650°C for 4 h in a reduction atmosphere (N2+CO). The structure and morphology of obtained powders were analyzed by XRD and SEM/EDS methods, respectively. Optical properties were investigated by excitation, emission and reflection spectra and compared to photoluminescence properties of standard YAG:Ce. The obtained specimens show the significant effect of synthesis parameters on the phase composition and intensity of emission of M-α-Sialon:Eu2+powder.

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