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 A Novel Polymethyl Methacrylate Derivative Grafted with Cationic Iridium(III) Complex Units: Synthesis and Application in White Light-Emitting Diodes

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 499 ◽  
Author(s):  
Huaijun Tang ◽  
Xueyan Dong ◽  
Mingxian Chen ◽  
Qiuhong Chen ◽  
Mengran Ren ◽  
...  
Keyword(s):  
Polymethyl Methacrylate ◽  
White Light ◽  
Light Emitting Diodes ◽  
Thermal Quenching ◽  
Decomposition Temperature ◽  
Color Temperature ◽  
Light Emitting ◽  
White Leds ◽  
Orange Yellow ◽  
Cie Chromaticity

A novel orange-yellow-emitting polymethyl methacrylate derivative grafted with cationic iridium(III) complex units was synthesized and used as down-conversion luminescent materials in light-emitting diodes (LEDs). The polymer had a thermal decomposition temperature (Td) of 275 °C. With the temperature increasing from 20 to 100 °C, its photoluminescent intensity decreased to 76.8% with thermal quenching activation energy (Ea) of 0.2775 eV. A series of LEDs was fabricated by 460 nm blue GaN chips and the polymer blended in silicone at different concentrations. At 4.0 wt %, a cold white LED was obtained, the correlated color temperature (CCT) was 10,050 K, color rendering index (CRI) was 71.2, luminous efficiency (ηL) was 5.3 lm·w−1, and Commission Internationale de L’Eclairage (CIE) chromaticity coordinates were (0.30, 0.24). At 5.0 wt.%, the LED emitted neutral white light, its CCT was 4938 K, CRI was 75, ηL was 13.8 lm·w−1, and the CIE value was (0.34, 0.27). At 5.5 wt %, 6.0 wt %, 7.0 wt %, and 8.0 wt %, the LEDs all emitted warm white light; their CCTs were 3446, 3093, 2557, and 2337 K, respectively; their CRIs were 73.6, 71.8, 63.8, and 59.0, respectively; their ηL were 18.1, 16.3, 14.8, and 13.7 lm·w−1, respectively; and their CIE values were (0.36, 0.30), (0.40, 0.35), (0.45, 0.38), and (0.50, 0.42), respectively. At 9.0 wt %, the blue light of GaN chip was completely absorbed by the polymer and only the orange-yellow light of the polymer emitted. The results suggested the polymer was a promising orange-yellow-emitting phosphor candidate for white LEDs, especially for warm white LEDs.

scholarly journals Employing SiO2 nano-particles in conformal and in-cup structures of 8500 K white LEDs

2021 ◽  
Vol 10 (3) ◽  
pp. 1709-1717
Author(s):  
My Hanh Nguyen Thi ◽  
Phung Ton That
Keyword(s):  
Blue Light ◽  
White Light ◽  
Sio2 Nanoparticles ◽  
Luminous Flux ◽  
Nano Particles ◽  
Color Temperature ◽  
Refractive Indices ◽  
Light Emitting ◽  
White Leds ◽  
White Light Emitting Diodes

SiO2 nano-particles have been examined in a distant phosphor structure for the elevated luminous quality and better consistency of white light-emitting diodes with angular-dependent associated color temperature (CCT). The luminous scattering ability could be increased by applying SiO2 nano-particles contain silicone to the outside of the phosphorus coating. In specific, the strength of blue light at wide angles is increased and differences in CCT can be minimized. In addition, owing to the sufficient refractive indices of silicone-containing SiO2 nanoparticles between the air and phosphorus layers, the luminous flux was improved. This new configuration decreases angular-dependent CCT deviations in the range of -700 to 700 from 1000 to 420 K. In comparison, at a 120 mA driving current, the rise of lumen flux increased by 2.25% relative to an usual distant phosphor structure without SiO2 nano-particles. As a result, in a distant phosphor structure, the SiO2 nano-particles could not only enhance the uniformity of illumination but also enhance the output of light.

Three-dimensional GaN dodecagonal ring structures for highly efficient phosphor-free warm white light-emitting diodes

Nanoscale ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 4686-4695 ◽  
Author(s):  
Young Chul Sim ◽  
Seung-Hyuk Lim ◽  
Yang-Seok Yoo ◽  
Min-Ho Jang ◽  
Sunghan Choi ◽  
...  
Keyword(s):  
White Light ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Three Dimensional ◽  
Light Emitting ◽  
White Leds ◽  
Highly Efficient ◽  
Warm White Light ◽  
Ring Structures ◽  
White Light Emitting Diodes

Multifaceted dodecagonal ring structures emit light of various colours with high efficiency and are demonstrated to be phosphor-free white LEDs.

Novel polygonal structure Mn4+ activated In3+-based Elpasolite-type hexafluorides red phosphor for warm white light-emitting diodes (WLEDs)

2019 ◽  
Vol 48 (4) ◽  
pp. 1376-1385 ◽  
Author(s):  
Feng Hong ◽  
Haiming Cheng ◽  
Chao Song ◽  
Guixia Liu ◽  
Wensheng Yu ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Synthetic Methods ◽  
Red Phosphor ◽  
Light Emitting ◽  
White Leds ◽  
Red Phosphors ◽  
Polygonal Structure ◽  
Warm White Light ◽  
White Light Emitting Diodes

Red phosphors (NH4)2NaInF6:Mn4+ with controllable morphology were synthesized via different synthetic methods, which can be fabricated for warm white LEDs.

Perovskite white light-emitting diodes with a perovskite emissive layer blended with rhodamine 6G

2020 ◽  
Vol 8 (37) ◽  
pp. 12951-12958 ◽  
Author(s):  
Che-Yu Chang ◽  
Wei-Li Hong ◽  
Pei-Hsuan Lo ◽  
Tzu-Hsiang Wen ◽  
Sheng-Fu Horng ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Rhodamine 6G ◽  
Light Emitting ◽  
Emissive Layer ◽  
Chromaticity Coordinates ◽  
Halide Perovskites ◽  
Cie Chromaticity ◽  
White Light Emitting Diodes

Perovskite white light-emitting diodes with only a single emissive layer of halide perovskites and rhodamine 6G were realized with the CIE chromaticity coordinates of (0.33, 0.40).

Synthesis, structure and luminescence properties of new blue-green-emitting garnet-type Ca3Zr2SiGa2O12:Ce3+ phosphor for near-UV pumped white-LEDs

RSC Advances ◽  
2016 ◽  
Vol 6 (3) ◽  
pp. 2155-2161 ◽  
Author(s):  
Jiyou Zhong ◽  
Weidong Zhuang ◽  
Xianran Xing ◽  
Ronghui Liu ◽  
Yanfeng Li ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Luminescence Properties ◽  
Light Emitting ◽  
White Leds ◽  
White Light Emitting Diodes

A new blue-green-emitting garnet-type phosphor Ca3Zr2SiGa2O12:Ce3+ has been explored for n-UV pumped white light-emitting diodes.

Eu2+-activated full color orthophosphate phosphors for warm white light-emitting diodes

RSC Advances ◽  
2014 ◽  
Vol 4 (62) ◽  
pp. 33114-33119 ◽  
Author(s):  
Chenglong Zhao ◽  
Zhiguo Xia ◽  
Molin Li
Keyword(s):  
White Light ◽  
Potential Application ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
White Leds ◽  
Full Color ◽  
Warm White Light ◽  
White Light Emitting Diodes

Eu2+-activated full-color versatile orthophosphate phosphors can find potential application in warm white LEDs.

Synthesis of narrow-band red-emitting K2SiF6:Mn4+ phosphors for a deep red monochromatic LED and ultrahigh color quality warm-white LEDs

2015 ◽  
Vol 3 (3) ◽  
pp. 607-615 ◽  
Author(s):  
Ji Hye Oh ◽  
Heejoon Kang ◽  
Yun Jae Eo ◽  
Hoo Keun Park ◽  
Young Rag Do
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Narrow Band ◽  
Light Emitting ◽  
White Leds ◽  
Color Quality ◽  
Warm White Light ◽  
White Light Emitting Diodes

In this study, we synthesized and characterized narrow-band red-emitting K2SiF6:Mn4+ phosphors in order to improve the color qualities of warm white light-emitting diodes (LEDs).

Luminescence Properties and Synthesis of SrMgAl10O17:Mn4+ Red Phosphor for White Light-Emitting Diodes

2016 ◽  
Vol 16 (4) ◽  
pp. 3489-3493 ◽  
Author(s):  
Renping Cao ◽  
Hongdong Xue ◽  
Xiaoguang Yu ◽  
Fen Xiao ◽  
Donglan Wu ◽  
...  
Keyword(s):  
Red Light ◽  
Solid State Reaction Method ◽  
Luminescence Properties ◽  
Conventional Solid State Reaction ◽  
Light Emitting ◽  
White Leds ◽  
Structure Morphology ◽  
Optimal Doping Concentration ◽  
Cie Chromaticity ◽  
White Light Emitting Diodes

A series of Mn4+ doped SrMgAl10O17 phosphors are synthesized by a conventional solid-state reaction method in air, and their crystal structure, morphology, and fluorescence properties are investigated. The luminescence properties show clearly that SrMgAl10O17:Mn4+ phosphor can be excited by UV (200–380 nm), near UV (380–420 nm), and blue (420–480 nm) bands of LEDs chip, and emits red light in the range of 600 nm to 750 nm with satisfying CIE chromaticity coordinates (0.7207, 0.2793). The optimal doping concentration of Mn4+ ion is ∼1 mol%, and its lifetime is ∼1.15 ms. The possible luminous mechanism of Mn4+ ion is discussed by Tanabe-Sugano diagram. These experiment results indicate that Mn4+ doped SrMgAl10O17 phosphors can be a potential application as a red-emitting phosphor candidate in white LEDs.

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