scholarly journals Single-step-fabricated disordered metasurfaces for enhanced light extraction from LEDs

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Peng Mao ◽  
Changxu Liu ◽  
Xiyan Li ◽  
Mengxia Liu ◽  
Qiang Chen ◽  
...  
Keyword(s):  
Information Technologies ◽  
Visible Spectrum ◽  
Cost Effective ◽  
Single Step ◽  
Light Extraction ◽  
Light Sources ◽  
Fibre Optics ◽  
Light Emitting ◽  
Air Interface ◽  
Industrial Level

AbstractWhile total internal reflection (TIR) lays the foundation for many important applications, foremost fibre optics that revolutionised information technologies, it is undesirable in some other applications such as light-emitting diodes (LEDs), which are a backbone for energy-efficient light sources. In the case of LEDs, TIR prevents photons from escaping the constituent high-index materials. Advances in material science have led to good efficiencies in generating photons from electron–hole pairs, making light extraction the bottleneck of the overall efficiency of LEDs. In recent years, the extraction efficiency has been improved, using nanostructures at the semiconductor/air interface that outcouple trapped photons to the outside continuum. However, the design of geometrical features for light extraction with sizes comparable to or smaller than the optical wavelength always requires sophisticated and time-consuming fabrication, which causes a gap between lab demonstration and industrial-level applications. Inspired by lightning bugs, we propose and realise a disordered metasurface for light extraction throughout the visible spectrum, achieved with single-step fabrication. By applying such a cost-effective light extraction layer, we improve the external quantum efficiency by a factor of 1.65 for commercialised GaN LEDs, demonstrating a substantial potential for global energy-saving and sustainability.

scholarly journals Enhanced Light Extraction of Flip-Chip Mini-LEDs with Prism-Structured Sidewall

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 319 ◽  
Author(s):  
Bin Tang ◽  
Jia Miao ◽  
Yingce Liu ◽  
Hui Wan ◽  
Ning Li ◽  
...  
Keyword(s):  
Total Internal Reflection ◽  
Flip Chip ◽  
Extraction Efficiency ◽  
Light Output ◽  
Cost Effective ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Light Output Power ◽  
Light Emitting ◽  
Air Interface

Current solutions for improving the light extraction efficiency of flip-chip light-emitting diodes (LEDs) mainly focus on relieving the total internal reflection at sapphire/air interface, but such methods hardly affect the epilayer mode photons. We demonstrated that the prism-structured sidewall based on tetramethylammonium hydroxide (TMAH) etching is a cost-effective solution for promoting light extraction efficiency of flip-chip mini-LEDs. The anisotropic TMAH etching created hierarchical prism structure on sidewall of mini-LEDs for coupling out photons into air without deteriorating the electrical property. Prism-structured sidewall effectively improved light output power of mini-LEDs by 10.3%, owing to the scattering out of waveguided light trapped in the gallium nitride (GaN) epilayer.

Light Design and Textiles

2019 ◽  
pp. 33-37
Author(s):  
Yuri Nazarov Nazarov
Keyword(s):  
Information Technologies ◽  
Electric Energy ◽  
Electronic Textiles ◽  
Fibre Optics ◽  
Light Emitting ◽  
Textile Materials ◽  
Electronic Engineering ◽  
Unusual Product ◽  
Combining Information ◽  
Functional Purpose

Innovation textile is a new and unusual product type combining information technologies with wide art opportunities. The article considers three types of innovation textiles selected using the functional purpose principle: materials radiating light (electrofluorescence, light emitting diodes, including organic and fibre optics), materials forming an image (LC screens, OLED, LCD) and materials with fluorescence effect. A new cloth type named electronic textiles is a material, which conducts and at the same time consumes electric energy. It combined three formerly independent spheres: textiles, electrical engineering and electronic engineering. Textile materials are the base, on which various electronic devices are mounted.

High Temperature Performance Evaluation and Life Prediction for Titanium Modified Silicone Used in Light-Emitting Diodes Chip Scale Packages

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Si Yu ◽  
Zhen Wang ◽  
Jiajie Fan ◽  
Cheng Qian ◽  
Zhentao Deng ◽  
...  
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Heat Dissipation ◽  
Light Emitting Diodes ◽  
Temperature Stability ◽  
Cost Effective ◽  
Practical Significance ◽  
Light Sources ◽  
High Temperature Stability ◽  
Light Emitting

Abstract Light-emitting diodes (LED) chip scale packages (CSPs) have been promoted as a new light source with many advantages in smaller package size, lower material and process cost, and better heat dissipation effect. However, as it is exposed in harsh environments such as high temperature, high humidity, and high blue light irradiation, silicone material used in LED CSPs always suffers deterioration, which will seriously affect the LED's reliability and working life. Thus, the preparation of high reliable silicone has practical significance to promote the application of LED CSPs in lighting. In this research, titanium was introduced into the molecular chain of phenyl silicone by using the hydrolysis condensation method. A high temperature aging test was then performed to the prepared silicone before and after modification, and their optical, thermomechanical, and dielectric properties were characterized to evaluate their reliabilities. The results show that: (1) the Arrhenius function with the dielectric property as an aging characterization can be used as a temperature accelerated life model to predict the service life of the prepared silicone and (2) the titanium modified silicone can advance the high temperature stability on optical properties, thermomechanical, and dielectric properties and enhance the life expectancy. The major contributions of this study are to support the improvement of the novel LED CSP packaging materials and processes, and also to provide the technical guidance on the fast, accurate, and cost-effective reliability assessment for high-quality LED light sources.

scholarly journals An Introduction to Light-emitting Diodes

HortScience ◽  
2008 ◽  
Vol 43 (7) ◽  
pp. 1944-1946 ◽  
Author(s):  
C. Michael Bourget
Keyword(s):  
Light Emitting Diodes ◽  
Arc Discharge ◽  
Visible Spectrum ◽  
Constant Current ◽  
Light Sources ◽  
Total System ◽  
Light Emitting ◽  
Fluorescent Lamps ◽  
Materials Used ◽  
Incandescent Lamps

Light-emitting diodes (LEDs) are semiconductor devices that produce noncoherent, narrow-spectrum light when forward voltage is applied. LEDs range in wavelength from the UVC band to infrared (IR) and are available in packages ranging from milliwatts to more than 10 W. The first LED was an IR-emitting device and was patented in 1961. In 1962, the first practical visible spectrum LED was developed. The first high-power (1-W) LEDs were developed in the late 1990s. LEDs create light through a semiconductor process rather than with a superheated element, ionized gas, or an arc discharge as in traditional light sources. The wavelength of the light emitted is determined by the materials used to form the semiconductor junction. LEDs produce more light per electrical watt than incandescent lamps with the latest devices rivaling fluorescent tubes in energy efficiency. They are solid-state devices, which are much more robust than any glass-envelope lamp and contain no hazardous materials like fluorescent lamps. LEDs also have a much longer lifetime than incandescent, fluorescent, and high-density discharge lamps (U.S. Dept. of Energy). Although LEDs possess many advantages over traditional light sources, a total system approach must be considered when designing an LED-based lighting system. LEDs do not radiate heat directly, but do produce heat that must be removed to ensure maximum performance and lifetime. LEDs require a constant-current DC power source rather than a standard AC line voltage. Finally, because LEDs are directional light sources, external optics may be necessary to produce the desired light distribution. A properly designed LED light system is capable of providing performance and a lifetime well beyond any traditional lighting source.

Organic Light Emitting Diodes - Innovative Light Sources

2019 ◽  
pp. 101-107
Author(s):  
Sergei A. Stakharny
Keyword(s):  
Light Source ◽  
Organic Light Emitting Diodes ◽  
Organic Leds ◽  
Light Sources ◽  
High Quality ◽  
Light Emitting ◽  
Organic Light ◽  
Lighting Systems ◽  
Physical Principles ◽  
Prospects Of Application

This article is a review of the new light source – organic LEDs having prospects of application in general and special lighting systems. The article describes physical principles of operation of organic LEDs, their advantages and principal differences from conventional non-organic LEDs and other light sources. Also the article devoted to contemporary achievements and prospects of development of this field in the spheres of both general and museum lighting as well as other spheres where properties of organic LEDs as high-quality light sources may be extremely useful.

scholarly journals Application of Light-Emitting Diodes for Improving the Nutritional Quality and Bioactive Compound Levels of Some Crops and Medicinal Plants

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1477
Author(s):  
Woo-Suk Jung ◽  
Ill-Min Chung ◽  
Myeong Ha Hwang ◽  
Seung-Hyun Kim ◽  
Chang Yeon Yu ◽  
...  
Keyword(s):  
Plant Growth ◽  
In Vitro Culture ◽  
Light Emitting Diodes ◽  
Photosynthetic Pigment ◽  
Antioxidant Properties ◽  
Light Sources ◽  
Light Emitting ◽  
Cell Defense ◽  
Led Irradiation

Light is a key factor that affects phytochemical synthesis and accumulation in plants. Due to limitations of the environment or cultivated land, there is an urgent need to develop indoor cultivation systems to obtain higher yields with increased phytochemical concentrations using convenient light sources. Light-emitting diodes (LEDs) have several advantages, including consumption of lesser power, longer half-life, higher efficacy, and wider variation in the spectral wavelength than traditional light sources; therefore, these devices are preferred for in vitro culture and indoor plant growth. Moreover, LED irradiation of seedlings enhances plant biomass, nutrient and secondary metabolite levels, and antioxidant properties. Specifically, red and blue LED irradiation exerts strong effects on photosynthesis, stomatal functioning, phototropism, photomorphogenesis, and photosynthetic pigment levels. Additionally, ex vitro plantlet development and acclimatization can be enhanced by regulating the spectral properties of LEDs. Applying an appropriate LED spectral wavelength significantly increases antioxidant enzyme activity in plants, thereby enhancing the cell defense system and providing protection from oxidative damage. Since different plant species respond differently to lighting in the cultivation environment, it is necessary to evaluate specific wavebands before large-scale LED application for controlled in vitro plant growth. This review focuses on the most recent advances and applications of LEDs for in vitro culture organogenesis. The mechanisms underlying the production of different phytochemicals, including phenolics, flavonoids, carotenoids, anthocyanins, and antioxidant enzymes, have also been discussed.

scholarly journals 38 Using pooled data for single-step genomic prediction: Impact of within-pool variance and size

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 9-9
Author(s):  
Johnna L Baller ◽  
Stephen D Kachman ◽  
Larry A Kuehn ◽  
Matthew L Spangler
Keyword(s):  
Phenotypic Variation ◽  
Equal Opportunity ◽  
Cost Effective ◽  
Single Step ◽  
Pool Size ◽  
Individual Data ◽  
Phenotypic Data ◽  
Breeding Values ◽  
Mean Values ◽  
Genetic Evaluations

Abstract Economically relevant traits (ERT) are routinely collected within commercial segments of the beef industry but are rarely included in genetic evaluations because of unknown pedigrees. Individual relationships could be resurrected with genomics, which would be costly; pooling DNA and phenotypic data provides a cost-effective solution. A simulated beef cattle population consisting of 15 generations was genotyped with approximately 50k markers (841 quantitative trait loci were located across the genome) and phenotyped for a moderately heritable trait. Individuals from generation 15 were included in pools (observed genotype and phenotype were mean values of a group). Estimated breeding values (EBV) were generated from a single-step GBLUP model. The effects of pooling strategy (random and minimizing or uniformly maximizing phenotypic variation), pool size (1, 2, 10, 20, 50, 100, or no data from generation 15), and generational gaps of genotyping on EBV accuracy (correlation of EBV with true breeding values) were quantified. Greatest EBV accuracies of sires and dams were observed when no gap between genotyped parents and pooled offspring occurred. The EBV accuracies resulting from pools were greater than no data from generation 15 regardless of sire or dam genotyping. Minimizing phenotypic variation increased EBV accuracy by 8% and 9% over random pooling and uniformly maximizing phenotypic variation, respectively. Pool size of 2 was the only scenario that did not significantly decrease EBV accuracy compared to individual data when pools were formed randomly or by uniformly maximizing phenotypic variation (P > 0.05). Pool sizes of 2, 10, 20, or 50 did not generally lead to EBV accuracies that were statistically different than individual data when pools were constructed to minimize phenotypic variation (P > 0.05). Pooled genotyping to garner commercial-level phenotypes for genetic evaluations seems plausible, although differences exist depending on pool size and pool formation strategy. The USDA is an equal opportunity employer.

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