Assessing the impact of the transition to Light Emitting Diodes based solar lighting systems in India

2013 ◽  
Vol 17 (4) ◽  
pp. 363-370 ◽  
Author(s):  
Santosh M. Harish ◽  
Shuba V. Raghavan ◽  
Milind Kandlikar ◽  
Gireesh Shrimali
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting ◽  
Solar Lighting ◽  
Lighting Systems ◽  
The Impact

Cost-Effective Light-Mixing Module for Solar-Lighting System Appended With Auxiliary RGBW Light-Emitting Diodes

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
An Chi Wei ◽  
Shih Chieh Lo ◽  
Ju-Yi Lee ◽  
Hong-Yih Yeh
Keyword(s):  
Light Source ◽  
Light Emitting Diodes ◽  
Cylindrical Tube ◽  
Cost Effective ◽  
Lighting System ◽  
Optical Efficiency ◽  
Light Emitting ◽  
Solar Lighting ◽  
Lighting Systems ◽  
Main Components

A light-mixing module consisting of a compound parabolic concentrator (CPC) and a light-mixing tube is proposed herein to realize a uniform and efficient solar-lighting system. In this lighting system, the sunlight collected into a fiber and then guided to an indoor destination is the principal light source, while an auxiliary light source including multiple red, green, blue, and white (RGBW) light-emitting diodes (LEDs) is controlled by an auto-compensating module. To mix the principal and the auxiliary sources and to realize the uniform illumination, the light-mixing tube was coated with BaSO4 and optimized as a cylindrical tube. The design of the light-mixing tube is described and discussed in this article. According to the simulated results, the uniformity and the optical efficiency of the designed light-mixing tube are 82.9% and 85.7%, respectively, while from the experimental results, the uniformity of 85.9% and the optical efficiency of 83.3% have been obtained. In terms of the common indoor-lighting standards and the specifications of commercial components used in lighting systems, the proposed light-mixing module has demonstrated the high uniformity and acceptable optical efficiency. Additionally, since the main components of the light-mixing module can be designed as plastic optics, a cost-effective light-mixing module and a profitable lighting system can be realized. Thus, the performance and the price of the proposed light-mixing module fit the demands of the illumination market, while the proposed system shows the potential for indoor solar-lighting applications.

Studies of Degradation in Nichia AlGaN/InGaN/GaN Blue Light Emitting Diodes Under Close to Normal Operating Conditions

1996 ◽  
Vol 421 ◽  
Author(s):  
M. Osiński ◽  
D. L. Barton ◽  
C. J. Helms ◽  
P. Perlin ◽  
N. H. Berg ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Emitting Diodes ◽  
Defect Density ◽  
Degradation Process ◽  
Operating Conditions ◽  
Similar Amount ◽  
Life Testing ◽  
Light Emitting ◽  
High Pulsed Current ◽  
The Impact

AbstractThe reliability of devices fabricated in GaN and related alloys, especially under high current densities as would be found in lasers, has yet to be fully characterized. Our previous work [1] investigated the degradation of GaN-based blue light emitting diodes (LEDs) under high pulsed current stress. This work indicated a possible correlation between the high crystal defect density and failures caused by metal migration along these defect tubes. To assess the impact of this data on devices under more normal conditions, several LEDs from both older and more recent production lots were placed in a controlled temperature and current environment for several thousand hours. The test started with a constant 20 mA current for the first 1000 hours and continued for another 1650 hours at various currents up to 70 mA, all at a temperature of 23 °C. During this test, one of the older generation LED's output degraded by more than 50%. Subsequent failure analysis showed that this was caused by a crack which isolated part of the active region from the p-contact. The remaining LEDs were returned to life testing where the temperature was subsequently increased by 5 °C after each 500 hours of testing. The output from one of the newer LEDs dreiven at 70 mA degraded to 55% of its original value after 3600 hours and a second newer LED degraded by a similar amount after 4400 hours. The first failure, LED #16, did not exhibit a significant change in its I-V characteristics indicating that a change in the package transparency was a likely cause for the observed degradation. The second failure, LED #17, did show a noticeable change in its I-V characteristics. This device was subsequently returned to life testing where the degradation process will be monitored for further changes.

scholarly journals Carotenoid biosynthesis of pak choi (Brassica rapassp.chinensis) sprouts grown under different light-emitting diodes during the diurnal course

2018 ◽  
Vol 17 (10) ◽  
pp. 1289-1300 ◽  
Author(s):  
K. Frede ◽  
M. Schreiner ◽  
R. Zrenner ◽  
J. Graefe ◽  
S. Baldermann
Keyword(s):  
Light Emitting Diodes ◽  
Carotenoid Biosynthesis ◽  
Pak Choi ◽  
Light Emitting ◽  
Diurnal Course ◽  
The Impact

This study highlights the impact of LEDs on the carotenoid biosynthesis in pak choi throughout the day.

scholarly journals Long-Term Comparison of Attraction of Flying Insects to Streetlights after the Transition from Traditional Light Sources to Light-Emitting Diodes in Urban and Peri-Urban Settings

2019 ◽  
Vol 11 (22) ◽  
pp. 6198 ◽  
Author(s):  
Roy H. A. van Grunsven ◽  
Julia Becker ◽  
Stephanie Peter ◽  
Stefan Heller ◽  
Franz Hölker
Keyword(s):  
Light Emitting Diodes ◽  
Spectral Composition ◽  
Mercury Vapor ◽  
World Market ◽  
Relative Difference ◽  
Urban Setting ◽  
Light Sources ◽  
Urban Settings ◽  
Light Emitting ◽  
The Impact

Among the different light sources used for street lighting, light-emitting diodes (LEDs) are likely to dominate the world market in the coming years. At the same time, the spectral composition of nocturnal illumination is changing. Europe and many other areas worldwide have implemented bans on energy-inefficient lamps, such as the still very common mercury vapor lamps. However, the impact of artificial light on insects is mostly tested with light-traps or flight-intercept traps that are used for short periods only. By comparing the numbers of insects attracted by street lamps before and after replacing mercury vapor light sources (MV) with light emitting diodes, we assessed the impact in more typical (urban and peri-urban) settings over several years. We found that LED attracted approximately half of the number of insects compared to MV lights. Furthermore, most insect groups are less drawn by LED than by MV, while Hymenoptera are less attracted by MV than by LED. Thus, the composition of the attracted communities differed between the light sources, which may impact ecosystem processes and functions. In green peri-urban settings more insects are attracted than in an urban setting, but the relative difference between the light sources is the same.

The impact of active layer design on quantum efficiency of InGaN light emitting diodes

2012 ◽  
Author(s):  
F. Zhang ◽  
X. Li ◽  
S. Okur ◽  
V. Avrutin ◽  
Ü. Özgür ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Active Layer ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
The Impact

scholarly journals Assessment of the optical and electrical properties of light-emitting diodes containing carbon-based nanostructures and plasmonic nanoparticles: a review

2021 ◽  
Vol 12 ◽  
pp. 1078-1092
Author(s):  
Keshav Nagpal ◽  
Erwan Rauwel ◽  
Frédérique Ducroquet ◽  
Protima Rauwel
Keyword(s):  
Thermal Management ◽  
Carbon Nanostructures ◽  
Light Emitting Diodes ◽  
Plasmonic Nanoparticles ◽  
Device Performance ◽  
Optical And Electrical Properties ◽  
Light Emitting ◽  
Flexible Devices ◽  
Turn On ◽  
Lighting Systems

Light-emitting diodes (LED) are widely employed in display applications and lighting systems. Further research on LED that incorporates carbon nanostructures and metal nanoparticles exhibiting surface plasmon resonance has demonstrated a significant improvement in device performance. These devices offer lower turn-on voltages, higher external quantum efficiencies, and luminance. De facto, plasmonic nanoparticles, such as Au and Ag have boosted the luminance of red, green, and blue emissions. When combined with carbon nanostructures they additionally offer new possibilities towards lightweight and flexible devices with better thermal management. This review surveys the diverse possibilities to combine various inorganic, organic, and carbon nanostructures along with plasmonic nanoparticles. Such combinations would allow an enhancement in the overall properties of LED.

scholarly journals Effect of Inhomogeneous Broadening in Ultraviolet III-Nitride Light-Emitting Diodes

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7890
Author(s):  
Friedhard Römer ◽  
Martin Guttmann ◽  
Tim Wernicke ◽  
Michael Kneissl ◽  
Bernd Witzigmann
Keyword(s):  
Active Region ◽  
Quantum Wells ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Inhomogeneous Broadening ◽  
Aluminium Content ◽  
Hole Density ◽  
Free Hole ◽  
Light Emitting ◽  
The Impact

In the past years, light-emitting diodes (LED) made of GaN and its related ternary compounds with indium and aluminium have become an enabling technology in all areas of lighting. Visible LEDs have yet matured, but research on deep ultraviolet (UV) LEDs is still in progress. The polarisation in the anisotropic wurtzite lattice and the low free hole density in p-doped III-nitride compounds with high aluminium content make the design for high efficiency a critical step. The growth kinetics of the rather thin active quantum wells in III-nitride LEDs makes them prone to inhomogeneous broadening (IHB). Physical modelling of the active region of III-nitride LEDs supports the optimisation by revealing the opaque active region physics. In this work, we analyse the impact of the IHB on the luminescence and carrier transport III-nitride LEDs with multi-quantum well (MQW) active regions by numerical simulations comparing them to experimental results. The IHB is modelled with a statistical model that enables efficient and deterministic simulations. We analyse how the lumped electronic characteristics including the quantum efficiency and the diode ideality factor are related to the IHB and discuss how they can be used in the optimisation process.

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