LEDs ♦ news digest PhotonStar to host major
LED lighting event The III-V nitride firm will be instrumental in this global sustainable design event
Considering that the solar spectrum is an intrinsically broadband spectrum, such broadband characteristics of the AR coating are undoubtedly beneficial for high power conversion efficiency.
What’s more, omnidirectional AR characteristics have become important for the rapidly expanding terrestrial application of solar cells. This is because solar irradiance in terrestrial applications usually has a large range of incident angles for non-tracking solar cells.
Both broadband and omnidirectional AR characteristics are attainable by four-layer AR coatings, as demonstrated by the RPI-led team.
RPI says that the excellent broadband and omnidirectional AR characteristics of the four-layer AR coating are achieved through solving the problem of refractive index matching at multiple layer interfaces.
By using tailored and low-refractive index nanoporous silica layers, the team has greatly reduced the refractive index contrast at the semiconductor / AR coating / air interfaces.
Through a multilayer design methodology powered by a genetic algorithm optimisation, favourable antireflective properties over a specified wavelength range and angle-of-incidence range were found.
Two porous layers of the four-layer AR coating were fabricated by oblique-angle deposition of silica thereby resulting in films with refractive indices of 1.32 and 1.11. This is less than the refractive index of silica. The other two layers are dense and were fabricated by co-deposition of silica / titania using sputtering.
According to the photocurrent measurements performed by the team, the angle-of-incidence (0°- 80°) averaged photocurrent enhancement (over an uncoated triple-junction solar cell) of the four-layer AR coating amounts to 34.4 percent. The enhancement of a DLAR coating is only 25.3 percent.
In the future, the team members Jaehee Cho and E. Fred Schubert, will integrate this novel AR coating technology on surface-textured devices.
They will also investigate innovative fabrication methods for depositing low-refractive index AR coatings on curved surfaces, such as a hemispherical lens.
Further details of this research are described in the paper, “Enhanced Omnidirectional Photovoltaic Performance of Solar Cells Using Multiple-Discrete-Layer Tailored - and Low-Refractive Index Anti-Reflection Coatings,” by X. Yan et al in Advanced Functional Materials, 23, 583 (2013).
PhotonStar LED Group plc, a British designer and manufacturer of smart LED lighting solutions, will be the primary sponsor this year for EcoBuild’s 300m2 lighting feature “Evolution of Light”.
With a visitor count of 60,000, it is a key event on the global architectural calendar.
The “Evolution of Light” feature, housed inside three giant connected domes, will take visitors on a dynamic audio visual journey through light, providing visitors with essential information about our biological lighting needs, lighting energy challenges, and lighting in the future connected world.
The feature will demonstrate the latest ChromaWhite dynamic lighting solutions from PhotonStar controlled by Pharos lighting controllers.
Representatives from key industry bodies and other manufacturers will be supporting PhotonStar and contributing to the feature to provide the very best educational experience.
Visitors will be able to interact with the installations through their smartphones and can ask questions or talk to professionals with knowledge and experience of all aspects of lighting.
A comprehensive seminar programme will also run throughout the exhibition, educating visitors about the most pertinent issues affecting the lighting industry, and setting out many of the possibilities for the future. This educational programme will be delivered by PhotonStar and other experts in the lighting industry, who will provide trusted advice and responsible solutions.
Separating the core and shell
of CdSe quantum dots LEDs, solar cells and sensors could benefit from a new technology to study the interface between the core and shell of quantum dots composed of CdTe based materials
The J. William Fulbright College of Arts & Sciences at the University of Arkansas, has received a $650,000 award from the National Science Foundation.
Colin Heyes, an assistant professor in the department of chemistry and biochemistry in the institute was instrumental in receiving the award.
The Faculty Early Career Development Program award was given to further his investigation of the interfaces between the core and shell of colloidal quantum dots.
Colloidal quantum dots are microscopic semiconductor crystals March 2013
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