Phosphor-Conversion White Light Emitting Diode Using InGaN Near-Ultraviolet Chip

2007 ◽  
Vol 124-126 ◽  
pp. 499-502 ◽  
Author(s):  
Kyoung Jae Choi ◽  
Joung Kyu Park ◽  
Kyung Nam Kim ◽  
Chang Hae Kim ◽  
Ho Kun Kim
Keyword(s):  
White Light ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Forward Bias ◽  
Color Temperature ◽  
Operating Voltage ◽  
Current Increase ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
Yellow Region

We have synthesized a Eu2+-activated Sr3MgSi2O8 blue phosphor and (Sr,Ba)2SiO4 yellow phosphor. We fabricated a phosphor-conversion white light emitting diode(LED) using an InGaN chip that emits 400 nm near-ultraviolet(n-UV) light and phosphors that emit in the blue and yellow region. When the white LED was operated at a forward-bias current of 20 mA at room temperature(RT), the color temperature(Tcp), average color rendering(Ra), operating voltage(Vf) and luminous efficacy(ηL) were estimated to be 5800K, 72.08, 3.4V, and 7.61 lm/W, respectively. The commission International de I’Eclarirage(CIE) chromaticity coordinates obtained from the measured spectra remained almost constant during the forward-baias current increase from 0.5 mA to 60 mA.

scholarly journals Chromaticity Study of Curcumin Dye Extracted from Curcuma longa L. Using for UV Light down Conversion for White Light Emitting Diode

2019 ◽  
Vol 290 ◽  
pp. 183-189
Author(s):  
Mahmood Al Shafouri ◽  
Naser Mahmoud Ahmed ◽  
Zainuriah Hassan ◽  
Munirah Abdullah Almessiere
Keyword(s):  
White Light ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Curcuma Longa ◽  
Color Temperature ◽  
Light Emitting ◽  
Chromaticity Coordinates ◽  
Major Factors ◽  
Color Rendering ◽  
Down Conversion

In thus study, Turmeric phosphor dye was extracted from Curcuma Longa L. via a simple technique using silica gel. The phosphor was used for light down-conversion of UV light for the manufacture white light emitting diode (WLED). The UV-LED was analyzed over 395nm wavelengths. The characteristics of the white light chromaticity were controlled by tuning the current and phosphor concentration. An optimum color rendering index (CRI) value of 63.4 was obtained. The chromaticity coordinates (CIE) and correlated color temperature (CCT) were measured for various currents and phosphor concentrations. The white phosphor exhibited CIE value of 0.355,0.338 and CCT of 4567 K. The concentration of phosphor and amount of applied current were confirmed to be major factors that control the intensity of white light emitted from the sample, where CIE and CRI of the emitted light steadily increased with the concentration of phosphor and current. Thus, phosphor concentration has a critical effect on conversion efficiency. Key words: Turmeric, phosphor, WLED, curcumin

scholarly journals Near Unity PLQY and High Stability of Barium Thiocyanate Based All-Inorganic Perovskites and Their Applications in White Light-Emitting Diodes

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 209
Author(s):  
Gopi Chandra Adhikari ◽  
Saroj Thapa ◽  
Yang Yue ◽  
Hongyang Zhu ◽  
Peifen Zhu
Keyword(s):  
White Light ◽  
Large Scale ◽  
Light Emitting Diode ◽  
Photophysical Properties ◽  
Environmental Stability ◽  
Color Temperature ◽  
Ambient Atmosphere ◽  
Light Emitting ◽  
Halide Perovskite ◽  
Lead Halide

All-inorganic lead halide perovskite (CsPbX3) nanocrystals (NCs) have emerged as a highly promising new generation of light emitters due to their extraordinary photophysical properties. However, the performance of these semiconducting NCs is undermined due to the inherent toxicity of lead and long-term environmental stability. Here, we report the addition of B-site cation and X-site anion (pseudo-halide) concurrently using Ba(SCN)2 (≤50%) in CsPbX3 NCs to reduce the lead and improve the photophysical properties and stability. The as-grown particles demonstrated an analogous structure with an almost identical lattice constant and a fluctuation of particle size without altering the morphology of particles. Photoluminescence quantum yield is enhanced up to near unity (~98%) by taking advantage of concomitant doping at the B- and X-site of the structure. Benefitted from the defect reductions and stronger bonding interaction between Pb2+ and SCN− ions, Ba(SCN)2-based NCs exhibit improved stability towards air and moisture compared to the host NCs. The doped NCs retain higher PLQY (as high as seven times) compared to the host NCs) when stored in an ambient atmosphere for more than 176 days. A novel 3D-printed multiplex color conversion layer was used to fabricate a white light-emitting diode (LED). The obtained white light shows a correlated color temperature of 6764 K, a color rendering index of 87, and luminous efficacy of radiation of 333 lm/W. In summary, this work proposes a facile route to treat sensitive lead halide perovskite NCs and to fabricate LEDs by using a low-cost large-scale 3-D printing method, which would serve as a foundation for fabricating high-quality optoelectronic devices for near future lighting technologies.

Optical and structural properties of curcuminoids extracted from Curcuma longa L. for hybrid white light diode

2018 ◽  
Vol 84 (1) ◽  
pp. 10501 ◽  
Author(s):  
M. Al Shafouri ◽  
Naser M. Ahmed ◽  
Z. Hassan ◽  
Munirah Abdullah Almessiere ◽  
Maadh Jumaah
Keyword(s):  
White Light ◽  
Dye Degradation ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Curcuma Longa ◽  
Stress Test ◽  
Air Gap ◽  
Color Temperature ◽  
Soxhlet Apparatus ◽  
Normal Method

In this study, curcuminoids were extracted from turmeric (Curcuma longa L.) by means of three methods, comprising the normal method, use of Soxhlet apparatus and by combining the normal method with the Soxhlet extraction approach. The limitation of stickiness in the use of curcuminoids was resolved by mixing it with silica gel. The curcuminoids used light down-conversion of UV light (390 nm) for the white light-emitting diode (WLED). The characteristics of the white light chromaticity were controlled by changing the current and concentration of the curcuminoids. The chromaticity coordinates (CIE) and correlated color temperature (CCT) were measured for different applied currents (20, 60 and 100 mA) and weights (25, 35 and 50 mg) of curcuminoids. It was observed from the concentration of phosphor that the combination of the normal and Soxhlet apparatus methods is most effective extraction approach. The results showed that increasing the concentration of phosphor significantly and remarkably increased the value of CCT when different values of current were applied. The stress test showed that the prolongation of dye degradation can be improved using air gap and glass slid, with air gap being more effective. An optimum color rendering index (CRI) value of 61.2 is obtained. The white phosphor exhibited CIE values of 0.333, 0.3151 and color temperature (CCT) of 5405 K.

Synthesis and luminescence properties of the red phosphor CaZrO3:Eu3+ for white light-emitting diode application

Open Physics ◽  
2011 ◽  
Vol 9 (4) ◽  
Author(s):  
Junli Huang ◽  
Liya Zhou ◽  
Yuwei Lan ◽  
Fuzhong Gong ◽  
Qunliang Li ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diode ◽  
Red Light ◽  
Average Diameter ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
Light Region

AbstractEu3+-doped CaZrO3 phosphor with perovskite-type structure was synthesized by the high temperature solid-state method. The samples were characterized by X-ray diffraction, scanning electron microscopy, fluorescence spectrophotometer and UV-vis spectrophotometer, respectively. XRD analysis showed that the formation of CaZrO3 was at the calcinations temperature of 1400°C. The average diameter of CaZrO3 with 4 mol% doped-Eu3+ was 2µm. The PL spectra demonstrated that CaZrO3:Eu3+ phosphor could be excited effectively in the near ultraviolet light region (397 nm) and emitted strong red-emission lines at 616 nm corresponding to the forced electric dipole 5 D 0 → 7 F 2 transitions of Eu3+. Meanwhile, the light-emitting diode was fabricated with the Ca0.96ZrO3:Eu0.043+ phosphor, which can efficiently absorb ∼ 400 nm irradiation and emit red light. Therefore Ca0.96ZrO3:Eu0.043+ may have applications for a near ultraviolet InGaN chip-based white light-emitting diode.

Near-ultraviolet chip-based phosphor-converted solar-spectrum white light-emitting diode

2020 ◽  
Vol 59 (01) ◽  
pp. 1
Author(s):  
Xinran Zhang ◽  
Shuo Zhang ◽  
Guodong Wang ◽  
Yunyu Wang ◽  
Meng Liang ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diode ◽  
Solar Spectrum ◽  
Light Emitting ◽  
Near Ultraviolet

The temperature-dependent luminescence properties of BaAl2−xSixO4−xNx:Eu2+ and its application in yellowish-green light emitting diode

2009 ◽  
Vol 24 (8) ◽  
pp. 2589-2595 ◽  
Author(s):  
Mei Zhang ◽  
Baohong Li ◽  
Jing Wang ◽  
Zhiyang Zhang ◽  
Qiuhong Zhang ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Forward Bias ◽  
Green Light ◽  
Thermal Quenching ◽  
Energy Shift ◽  
Light Emitting ◽  
Yellowish Green ◽  
Near Ultraviolet ◽  
Increasing Temperature ◽  
Cation Sites

The influences of (SiN)+ and Eu2+ concentration on the optical properties of BaAl2−xSixO4−xNx:Eu2+ were investigated. The lifetime results show that there are two different cation sites occupied by Eu2+ ions and the energy transfer occurs between them. The Huang–Rhys factor and the Stokes energy shift were determined, and thermal quenching with increasing temperature was observed. Finally, intense yellowish-green light emitting diodes (LED) with the color coordinate of (0.2936, 0.4483) under a forward-bias current of 20 mA was successfully fabricated on the basis of a structure consisting of BaAl2−xSixO4−xNx:Eu2+ phosphor and near-ultraviolet (∼395 nm) GaN chip.

A Single-Phase Full-Color Ca4Si2O7F2:Ce3+, Tb3+, Sm3+ Micron Belt Mat for White-Light Emitting Diode Application

2016 ◽  
Vol 697 ◽  
pp. 727-732 ◽  
Author(s):  
Bo Cui ◽  
Qing Hong Zhang ◽  
Hong Zhi Wang ◽  
Yao Gang Li
Keyword(s):  
Heat Treatment ◽  
White Light ◽  
Single Phase ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Electrospinning Process ◽  
Light Emitting ◽  
Full Color ◽  
Color Tunable ◽  
White Light Emitting Diodes

A new kind of Ca4Si2O7F2:Ce3+, Tb3+, Sm3+ oxyfluoride phosphor micron belt mat was obatained by simply electrospinning process and subsequent heat treatment. XRD result shows that a pure Ca4Si2O7F2 phase can be obtained at low temperature of around 900 °C. The micron belt precursor has a smooth surface and uniform morphology, and the width and thickness of the belt is about 2 μm and 200 nm. The morphology of micron belt is well retained after heat treatment, forming a plat phosphor mat consisting of uniform micron belt network. Ca4Si2O7F2:Ce3+, Ca4Si2O7F2:Tb3+, and Ca4Si2O7F2:Sm3+ exhibit the characteristic emissions of Ce3+ (4f7→4f65d1, blue), Tb3+ (4f8→4f75d, green), and Sm3+ (4f6→4f65d, red) under the excitation of near-UV light, respectively. By adjusting the doping concentration of Ce3+, Tb3+, Sm3+ ions a white emission in a single phase was obtained under the excitation of 360 nm. We have demonstrated that Ca4Si2O7F2:Ce3+, Tb3+, Sm3+ phosphor mat can be a promising candidate for a color-tunable phosphor mat applied in a near-UV White light emitting diodes.

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 CRI in phosphor-in-doped glass under near-ultraviolet excitation for warm white light-emitting diode

2021 ◽  
Vol 229 ◽  
pp. 117684
Author(s):  
A. Arellano-Morales ◽  
J. Molina-González ◽  
H. Desirena ◽  
J.M. Bujdud-Perez ◽  
S. Calixto
Keyword(s):  
White Light ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
Ultraviolet Excitation ◽  
Near Ultraviolet ◽  
Warm White Light ◽  
Doped Glass

scholarly journals Yellow Emission Obtained by Combination of Broadband Emission and Multi-Peak Emission in Garnet Structure Na2YMg2V3O12: Dy3+ Phosphor

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 542 ◽  
Author(s):  
Weiyi Zhang ◽  
Can He ◽  
Xiaowen Wu ◽  
Ximing Huang ◽  
Fankai Lin ◽  
...  
Keyword(s):  
Solid State ◽  
White Light ◽  
Emission Band ◽  
Uv Light ◽  
Light Emitting Diode ◽  
Color Temperature ◽  
Broad Emission Band ◽  
Yellow Emission ◽  
Conventional Solid State Reaction ◽  
Broad Emission

The fabrication and luminescent performance of novel phosphors Na2YMg2V3O12:Dy3+ were investigated by a conventional solid-state reaction method. Under near-UV light, the Na2YMg2V3O12 host self-activated and released a broad emission band (400–700 nm, with a peak at 524 nm) ascribable to charge transfer in the (VO4)3− groups. Meanwhile, the Na2YMg2V3O12:Dy3+ phosphors emitted bright yellow light within both the broad emission band of the (VO4)3- groups and the sharp peaks of the Dy3+ ions at 490, 582, and 663 nm at a quenching concentration of 0.03 mol. The emission of the as-prepared Na2YMg2V3O12:Dy3+ phosphors remained stable at high temperatures. The obtained phosphors, commercial Y2O3:Eu3+ red phosphors, and BaMgAl10O17:Eu2+ blue phosphors were packed into a white light-emitting diode (WLED) device with a near-UV chip. The designed WLED emitted bright white light with good chromaticity coordinates (0.331, 0.361), satisfactory color rendering index (80.2), and proper correlation to a color temperature (7364 K). These results indicate the potential utility of Na2YMg2V3O12:Dy3+ phosphor as a yellow-emitting phosphor in solid-state illumination.

Sign in / Sign up

Export Citation Format

Share Document