scholarly journals Specific Light-Emitting Diodes Can Suppress Sporulation of Podosphaera pannosa on Greenhouse Roses

Plant Disease ◽  
2010 ◽  
Vol 94 (9) ◽  
pp. 1105-1110 ◽  
Author(s):  
A. Suthaparan ◽  
S. Torre ◽  
A. Stensvand ◽  
M. L. Herrero ◽  
R. I. Pettersen ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
White Light ◽  
Light Emitting Diodes ◽  
Dark Period ◽  
Red Light ◽  
Suppressive Effect ◽  
Continuous Illumination ◽  
Light Emitting ◽  
Dark Interval ◽  
Red Leds

When rose plants bearing colonies of Podosphaera pannosa were placed in a wind tunnel, the number of conidia trapped was directly proportional to intensity of daylight-balanced (white) light from 5 to 150 μmol m–2 s–1. Illumination of samples using blue (420 to 520 nm) light-emitting diodes (LEDs) increased the number of conidia trapped by a factor of approximately 2.7 over white light but germination of conidia under blue light was reduced by approximately 16.5% compared with conidia germination under white light. The number of conidia trapped under far-red (>685 nm) LEDs was approximately 4.7 times higher than in white light, and 13.3 times higher than under red (575 to 675 nm) LEDs, and germination was not induced compared with white light. When mildewed plants were exposed to cycles of 18 h of white light followed by 6 h of blue, red, far-red light, or darkness, light from the red LEDs reduced the number of conidia trapped by approximately 88% compared with darkness or far-red light. Interrupting the above dark period with 1 h of light from red LEDs also reduced the number of conidia trapped, while a 1-h period of light from far-red following the 1 h of light from red LEDs nullified the suppressive effect of red light. Our results indicate that brief exposure to red light during the dark interval may be as effective as continuous illumination in suppressing powdery mildew in greenhouse rose plant (Rosa × hybrida).

(K0.5Na0.5)NbO3:Eu3+/Bi3+: a novel, highly efficient, red light-emitting material with superior water resistance behavior

RSC Advances ◽  
2015 ◽  
Vol 5 (6) ◽  
pp. 4707-4715 ◽  
Author(s):  
Qiwei Zhang ◽  
Haiqin Sun ◽  
Tao Kuang ◽  
Ruiguang Xing ◽  
Xihong Hao
Keyword(s):  
Blue Light ◽  
White Light ◽  
High Performance ◽  
Water Resistance ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Light Emitting ◽  
Highly Efficient ◽  
White Light Emitting Diodes

Materials emitting red light (∼611 nm) under excitation with blue light (440–470 nm) are highly desired for fabricating high-performance white light-emitting diodes (LEDs).

scholarly journals (Y,Gd)BO3:Eu red phosphor for dual-layer phosphor structure to enhance the optical performance of white light-emitting diodes

2021 ◽  
Vol 10 (4) ◽  
pp. 1930-1935
Author(s):  
Phan Xuan Le ◽  
Le Hung Tien
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Phosphor Layer ◽  
Light Emitting ◽  
Conformal Coating ◽  
Color Quality ◽  
Remote Phosphor ◽  
White Light Emitting Diodes ◽  
Color Rendering

Among the structures using for fabricating white light-emitting diodes (WLEDs) such as the conformal coating or in-cup geometries, the remote phosphor structure gives the highest luminous efficacy. However, in terms of color quality, its performance is not as good as the others. The red-light compensation has been reported as the effective solution for enhancing the color quality of WLEDs. Hence, this study adopted the idea and applied to the dual-layer phosphor structure. The phosphor used to boost the red color in light formation is (Y,Gd)BO3:Eu particle. The dual-layer remote phosphor structure was simulated with the red (Y,Gd)BO3:Eu phosphor layer above the original yellow phosphor YAG:Ce3+ one. The WLEDs with different correlated color temperatures of 5600 K, 6600 K and 7700K were experimented. Mie-theory and Lambert-Beer law were applied to examine the results. The growth in color rendering index (CRI) and color quality scale (CQS) with the increase of (Y,Gd)BO3:Eu phosphor concentration was observed. Nevertheless, the lumen efficacy would be degraded if the concentration was over a certain number. The information provided in this article is useful for the development of high-power WLED production with greater color quality.

scholarly journals Luminescence properties of novel red-emitting phosphor InNb1-xPxO4:Eu3+ for white light emitting-diodes

2015 ◽  
Vol 33 (2) ◽  
pp. 331-334 ◽  
Author(s):  
An Tang ◽  
Tao Ma ◽  
Liduo Gu ◽  
Yongtao Zhao ◽  
Junhui Zhang ◽  
...  
Keyword(s):  
White Light ◽  
Luminescence Intensity ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Emission Spectra ◽  
Luminescence Properties ◽  
Potential Candidate ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
White Light Emitting Diodes

AbstractInNb1-xPxO4:Eu3+ red phosphors were synthesized by solid-state reaction and their luminescence properties were also studied through photoluminescence spectra. The excitation and emission spectra make it clear that the as-prepared phosphors can be effectively excited by near-ultraviolet (UV) 394 nm light and blue 466 nm light to emit strong red light located at 612 nm, due to the Eu3+ transition of 5D0 → 7F2. The luminescence intensity is dependent on phosphorus content, and it achieves the maximum at x = 0.4. Excessive phosphorus in the phosphors can result in reduction of luminescence intensity owing to concentration quenching.With the increasing content of phosphorus, the phosphors are prone to emit pure red light. This shows that the InNb1.6P0.4O4:0.04Eu3+ phosphor may be a potential candidate as a red component for white light emitting-diodes.

Stress engineering for reducing the injection current induced blue shift in InGaN-based red light-emitting diodes

CrystEngComm ◽  
2021 ◽  
Author(s):  
Weizhen Yao ◽  
Lianshan Wang ◽  
Yulin Meng ◽  
Shaoyan Yang ◽  
Xianglin Liu ◽  
...  
Keyword(s):  
Sapphire Substrate ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Blue Shift ◽  
Ingan Layer ◽  
Patterned Sapphire Substrate ◽  
Light Emitting ◽  
Stress Engineering ◽  
Engineering Strategy ◽  
Red Leds

Red LEDs with a small blue shift are fabricated by using a stress engineering strategy through the growth of the pre-stained InGaN layer and dual-wavelength QWs on a cone-shape patterned sapphire substrate.

scholarly journals Growth, Nutritional Quality, and Energy Use Efficiency of Hydroponic Lettuce as Influenced by Daily Light Integrals Exposed to White versus White Plus Red Light-emitting Diodes

HortScience ◽  
2019 ◽  
Vol 54 (10) ◽  
pp. 1737-1744 ◽  
Author(s):  
Zhengnan Yan ◽  
Dongxian He ◽  
Genhua Niu ◽  
Qing Zhou ◽  
Yinghua Qu
Keyword(s):  
Nutritional Quality ◽  
Energy Use ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Dry Weight ◽  
Light Emitting ◽  
Energy Use Efficiency ◽  
White Leds ◽  
Use Efficiency ◽  
Red Leds

Few researchers examined different red light amounts added in white light-emitting diodes (LEDs) with varied daily light integrals (DLIs) for hydroponic lettuce (Lactuca sativa L.). In this study, effects of DLI and LED light quality (LQ) on growth, nutritional quality, and energy use efficiency of hydroponic lettuce were investigated in a plant factory with artificial lighting (PFAL). Hydroponic lettuce plants (cv. Ziwei) were grown for 20 days under 20 combinations of five levels of DLIs at 5.04, 7.56, 10.08, 12.60, and 15.12 mol·m−2·d−1 and four LQs: two kinds of white LEDs with red to blue ratio (R:B ratio) of 0.9 and 1.8, and two white LEDs plus red chips with R:B ratio of 2.7 and 3.6, respectively. Results showed that leaf and root weights and power consumption based on fresh and dry weights increased linearly with increasing DLI, and light and electrical energy use efficiency (LUE and EUE) decreased linearly as DLI increased. However, no statistically significant differences were found in leaf fresh and dry weights and nitrate and vitamin C contents between DLI at 12.60 and 15.12 mol·m−2·d−1. Also, no effects of LQ on leaf dry weight of hydroponic lettuce were observed at a DLI of 5.04 mol·m−2·d−1. White plus red LEDs with an R:B ratio of 2.7 resulted in higher leaf fresh weight than the two white LEDs. LUE increased by more than 20% when red light fraction increased from 24.2% to 48.6%. In summary, white plus red LEDs with an R:B ratio of 2.7 at DLI at 12.60 mol·m−2·d−1 were recommended for commercial hydroponic lettuce (cv. Ziwei) production in PFALs.

scholarly journals Growth and Carbohydrate Metabolism of Wheat Plants Grown with Red-light Emitting Diodes

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 863C-863
Author(s):  
N.C. Yorio ◽  
M. Sanwo ◽  
C.S. Brown
Keyword(s):  
Light Emitting Diodes ◽  
Starch Content ◽  
Red Light ◽  
Fold Increase ◽  
Sucrose Phosphate Synthase ◽  
Small Mass ◽  
Fluorescent Light ◽  
Light Emitting ◽  
Carbohydrate Concentration ◽  
Red Leds

Light-emitting diodes (LEDs) are a potential light source for growing plants in space flight systems because of their superior safety and reliability, small mass and volume, electrical efficiency, and longevity. To determine the influence of narrow-spectrum LEDs on plant growth and metabolism, wheat (Triticum aestivum L. `Superdwarf') plants were grown under red LEDs (peak emission 660 nm) and compared to plants grown under daylight fluorescent, red LEDs + 1% blue fluorescent light (BL), and red LEDs + 10% BL. Plants were taller, had longer flag leaves, and delayed seed development when grown under red LEDs or red LEDs + 1% BL compared to those grown with 10% BL or under daylight fluorescent. Viable seeds (290% germination) were produced in all plants regardless of the light treatment. Total dry matter (DM), head DM, and seed DM were similar in the plants grown under the four light regimes, and there were no differences in the starch content of the seeds. Starch levels were 4-times greater and sucrose levels were 2.5-times greater in leaves of plants grown under the red LEDs compared to daylight fluorescent. Daylight fluorescent leaves showed a 1.8-fold increase in sucrose phosphate synthase (SPS) activity, a regulatory enzyme of sucrose synthesis. These results indicate that wheat can be grown successfully under red LEDs, but there are differences in carbohydrate concentration and metabolism in photosynthetic tissue.

Phase-transition-induced giant enhancement of red emission in Mn4+-doped fluoride elpasolite phosphors

2018 ◽  
Vol 6 (15) ◽  
pp. 3951-3960 ◽  
Author(s):  
Yiwen Zhu ◽  
Daqin Chen ◽  
Lin Huang ◽  
Yong Liu ◽  
Mikhail G. Brik ◽  
...  
Keyword(s):  
Phase Transition ◽  
White Light ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Luminescence Properties ◽  
Red Emission ◽  
Light Emitting ◽  
Significant Interest ◽  
Light Components ◽  
White Light Emitting Diodes

Mn4+-Doped red fluoride phosphors have attracted significant interest of researchers because of their excellent luminescence properties that can address the issue of the lack of red light components in commercial white light-emitting-diodes (WLEDs).

Intense Red Light Emission of Eu3+-Doped Sr3B2SiO8for White Light-Emitting Diodes

2012 ◽  
Vol 159 (4) ◽  
pp. J107-J114 ◽  
Author(s):  
Jianfeng Sun ◽  
Wenlin Zhang ◽  
Dezhong Shen ◽  
Jiayue Sun
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Light Emission ◽  
Red Light ◽  
Light Emitting ◽  
White Light Emitting Diodes

scholarly journals Investigation of a Separated Short-Wavelength Peak in InGaN Red Light-Emitting Diodes

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1123
Author(s):  
Pavel Kirilenko ◽  
Zhe Zhuang ◽  
Daisuke Iida ◽  
Martin Velazquez-Rizo ◽  
Kazuhiro Ohkawa
Keyword(s):  
Quantum Wells ◽  
Short Wavelength ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Blue Shift ◽  
Light Emitting ◽  
Peak Emission Wavelength ◽  
Wavelength Emission ◽  
Main Emission Peak ◽  
Red Leds

We fabricated indium gallium nitride (InGaN) red light-emitting diodes (LEDs) with a peak emission wavelength of 649 nm and investigated their electroluminescence (EL) properties. An additional separated peak in the EL spectrum of the red LEDs at 20 mA was observed at 465 nm. This additional peak also exhibits a blue-shift with increasing currents as does the main emission peak. Using high-resolution microscopy, we observed many point-like emission spots in the EL emission images at the currents below 1 mA. However, these emission spots cannot be identified at currents above 5 mA because the red emission from quantum wells (QWs) is much stronger than that emitted by these spots. Finally, we demonstrate that these emission spots are related to the defects generated in red QWs. The measured In content was lower at the vicinity of the defects, which was regarded as the reason for separated short-wavelength emission in red InGaN LEDs.

scholarly journals Recent progress in red light-emitting diodes by III-nitride materials

2021 ◽  
Author(s):  
Daisuke Iida ◽  
Kazuhiro Ohkawa
Keyword(s):  
Recent Progress ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Strain Engineering ◽  
Research Field ◽  
Material System ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Highly Efficient ◽  
Red Leds

Abstract GaN-based light-emitting devices have the potential to realize all visible emissions with the same material system. These emitters are expected to be next-generation RGB displays and illumination tools. These emitting devices have been realized with highly efficient blue and green light-emitting diodes (LEDs) and laser diodes (LDs). Extending them to longer wavelength emissions remains challenging from an efficiency perspective. In the emerging research field of micro-LED displays, III-nitride red LEDs are in high demand to establish highly efficient devices like conventional blue and green systems. In this review, we describe fundamental issues in the development of red LEDs by III-nitrides. We also focus on the key role of growth techniques such as higher temperature growth, strain engineering, nanostructures, and Eu doping. The recent progress and prospect of developing III-nitride-based red light-emitting devices will be presented.

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