Dynamic Color Temperature White Lighting Source Based on Red Green and Blue Light Emitting Diode

2011 ◽  
Vol 31 (5) ◽  
pp. 0523004 ◽  
Author(s):  
殷录桥 Yin Luqiao ◽  
杨卫桥 Yang Weiqiao ◽  
李抒智 Li Shuzhi ◽  
程备 Cheng Bei ◽  
张建华 Zhang Jianhua
Keyword(s):  
Blue Light ◽  
Light Emitting Diode ◽  
Color Temperature ◽  
Light Emitting

scholarly journals A Novel Red-Emitting Na2NbOF5:Mn4+ Phosphor with Ultrahigh Color Purity for Warm White Lighting and Wide-Gamut Backlight Displays

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5317
Author(s):  
Jingshan Hou ◽  
Wenxiang Yin ◽  
Langping Dong ◽  
Yang Li ◽  
Yufeng Liu ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Emission ◽  
Light Emitting Diode ◽  
Red Light ◽  
Luminescent Properties ◽  
Fluorescence Decay ◽  
Color Temperature ◽  
Color Purity ◽  
Zero Phonon Line ◽  
Light Emitting

In this work, a novel red-emitting oxyfluoride phosphor Na2NbOF5:Mn4+ with an ultra-intense zero-phonon line (ZPL) was successfully synthesized by hydrothermal method. The phase composition and luminescent properties of Na2NbOF5:Mn4+ were studied in detail. The photoluminescence excitation spectrum contains two intense excitation bands centered at 369 and 470 nm, which match well with commercial UV and blue light-emitting diode (LED) chips. When excited by 470 nm blue light, Na2NbOF5:Mn4+ exhibits red light emission dominated by ZPL. Notably, the color purity of the Na2NbOF5:Mn4+ red phosphor can reach 99.9%. Meanwhile, the Na2NbOF5:Mn4+ phosphor has a shorter fluorescence decay time than commercial K2SiF6:Mn4+, which is conducive to fast switching of images in display applications. Profiting from the intense ZPL, white light-emitting diode (WLED) with high color rendering index of Ra = 86.2 and low correlated color temperature of Tc = 3133 K is realized using yellow YAG:Ce3+ and red Na2NbOF5:Mn4+ phosphor. The WLED fabricated using CsPbBr3 quantum dots (QDs) and red Na2NbOF5:Mn4+ phosphor shows a wide color gamut of 127.56% NTSC (National Television Standard Committee). The results show that red-emitting Na2NbOF5:Mn4+ phosphor has potential application prospects in WLED lighting and display backlight.

Color Offset in the Process of High-Power LED Life Aging

2016 ◽  
Vol 693 ◽  
pp. 498-503 ◽  
Author(s):  
L.Y. Zhang ◽  
Y.P. Cui ◽  
Z.N. Luo ◽  
L. Zhou
Keyword(s):  
Blue Light ◽  
White Light ◽  
High Power ◽  
Light Emitting Diodes ◽  
Light Emitting Diode ◽  
Color Temperature ◽  
Constant Current ◽  
Light Emitting ◽  
Color Coordinate ◽  
High Power Led

In order to study color offset of the high-power white light and blue light LED in the whole life, a series of high-power white light and blue light emitting diodes are lighted continuously under a constant current. In the light of different period of time, measured the light emitting diode emission spectrum, color coordinate, color temperature of the light emitting diodes are measured at different periods; light luminous flux, color coordinate and color temperature changes are also measured under different currents. The experimental results show that the color of LED is different at different period under the same current, and is also different under a variable current. The article studied the influence of different factors on the color offset, and pointed out that the high-power LED color offset is caused by not only phosphors aging but also more major changes of the material itself. Furthermore, the results will provide a reference to the application of white LED and for the further study.

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.

scholarly journals In vitro and in vivo Efficacy of New Blue Light Emitting Diode Phototherapy Compared to Conventional Halogen Quartz Phototherapy for Neonatal Jaundice

2005 ◽  
Vol 20 (1) ◽  
pp. 61 ◽  
Author(s):  
Yun Sil Chang ◽  
Jong Hee Hwang ◽  
Hyuk Nam Kwon ◽  
Chang Won Choi ◽  
Sun Young Ko ◽  
...  
Keyword(s):  
Blue Light ◽  
Neonatal Jaundice ◽  
Light Emitting Diode ◽  
In Vivo Efficacy ◽  
Light Emitting

scholarly journals Operando direct observation of spin-states and charge-trappings of blue light-emitting-diode materials in thin-film devices

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Fumiya Osawa ◽  
Kazuhiro Marumoto
Keyword(s):  
Blue Light ◽  
High Performance ◽  
Density Functional ◽  
Light Emitting Diode ◽  
Green Light ◽  
Spin States ◽  
Light Emitting ◽  
Full Color ◽  
Color Displays ◽  
Materials Used

Abstract Spin-states and charge-trappings in blue organic light-emitting diodes (OLEDs) are important issues for developing high-device-performance application such as full-color displays and white illumination. However, they have not yet been completely clarified because of the lack of a study from a microscopic viewpoint. Here, we report operando electron spin resonance (ESR) spectroscopy to investigate the spin-states and charge-trappings in organic semiconductor materials used for blue OLEDs such as a blue light-emitting material 1-bis(2-naphthyl)anthracene (ADN) using metal–insulator–semiconductor (MIS) diodes, hole or electron only devices, and blue OLEDs from the microscopic viewpoint. We have clarified spin-states of electrically accumulated holes and electrons and their charge-trappings in the MIS diodes at the molecular level by directly observing their electrically-induced ESR signals; the spin-states are well reproduced by density functional theory. In contrast to a green light-emitting material, the ADN radical anions largely accumulate in the film, which will cause the large degradation of the molecule and devices. The result will give deeper understanding of blue OLEDs and be useful for developing high-performance and durable devices.

Optimization and evaluation of a blue light photoinitiating system for textile inkjet printing

2018 ◽  
Vol 89 (10) ◽  
pp. 1964-1974
Author(s):  
Yi Huang ◽  
Guangdong Sun ◽  
Yating Ji ◽  
Dapeng Li ◽  
Qinguo Fan ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Emitting Diode ◽  
Absorption Efficiency ◽  
Polymerization Rate ◽  
Nozzle Clogging ◽  
Light Emitting ◽  
Custom Made ◽  
Light Curing ◽  
Set Up ◽  
Pigment Ink

A blue light curing process was developed to solve the nozzle clogging challenge commonly encountered in conventional textile pigment printing, by using camphorquinone (CQ) and ethyl-4-dimethylaminobenzoate (EDMAB) as a photoinitiator combination and substituting oligomers and monomers for a polymeric binder. High light absorption efficiency was insured by closely matching the spectrum of the photoinitiator with a custom-made blue light light-emitting diode set-up. Kinetic analyses of such a CQ/EDMAB system indicated that the maximum polymerization rate of the monomer was proportional to [PI]0.5 and [I0]0.5, while excessive high photoinitiator concentration (>1 wt%) will decrease the polymerization rate because of the “filter effect.” With optimized blue light curable pigment ink formula and irradiation conditions, the photocurable pigment printed fabrics exhibited uniform and vibrant colors, clear outlines, and excellent wet and dry rubbing fastness of grades 4 and 4–5, respectively.

scholarly journals Homogeneous ZnO nanowire arrays p-n junction for blue light-emitting diode applications

2019 ◽  
Vol 27 (16) ◽  
pp. A1207 ◽  
Author(s):  
Mingming Su ◽  
Tanglei Zhang ◽  
Jun Su ◽  
Zhao Wang ◽  
Yongming Hu ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Emitting Diode ◽  
Nanowire Arrays ◽  
Zno Nanowire ◽  
Light Emitting ◽  
Zno Nanowire Arrays

Enhanced performances of InGaN/GaN-based blue light-emitting diode with InGaN/AlInGaN superlattice electron blocking layer

2014 ◽  
Vol 23 (6) ◽  
pp. 068502
Author(s):  
Xiang-Jing Zhuo ◽  
Jun Zhang ◽  
Dan-Wei Li ◽  
Han-Xiang Yi ◽  
Zhi-Wei Ren ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Emitting Diode ◽  
Blocking Layer ◽  
Electron Blocking Layer ◽  
Light Emitting

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

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