Los Alamos National Laboratory (Next-Generation �

Los Alamos National Laboratory (Next-Generation “Giant” Quantum Dots: Performance-Engineered for Lighting) — The goal is to demonstrate a phosphor replacement as an enabling technology for high-performance LED luminaires.


University of California (Identification and Mitigation of Droop Mechanism in GaN-Based LEDs) — This project will focus on identifying the fundamental causes of current droop in state-of-the-art commercial LEDs.


Did you catch that thing about “droop” from the University of California and that other thing about quantum dots from Los Alamos National Laboratory? A couple of years ago the folks at Los Alamos were hot on the trail of a way to improve LED efficiency by deploying quantum dots to reduce droop, which refers to a drop in efficiency at high currents.

The Los Alamos team found that the culprit is something called Auger recombination, in which energy is dissipated as heat instead of light.

The same study also suggested a couple of different ways to overcome the obstacle, based on quantum dots made of a cadmium selenide core encased in a shell of cadmium sulfide.

We’re thinking that will come into play as the team forges ahead with its new Energy Department assignment, so stay tuned.

http://cleantechnica.com/2015/05/05/next-ligh...ntum-dots/



Recipient: Los Alamos National Laboratory (Los Alamos, NM)
Title: Next-Generation “Giant” Quantum Dots: Performance-Engineered for Lighting
Summary: This project seeks to develop quantum-dot down-converters to be used in LED lighting.

The focus will be on synthesizing red-emitting quantum dots , revealing their failure mechanisms, and

conducting accelerated lifetime testing on them.

The goal is to demonstrate a phosphor replacement as an enabling technology for high-performance LED luminaires.

DOE Share: $1,000,000; Cost Share: $250,000
http://energy.gov/eere/ssl/doe-announces-sele...t-round-10

........Giant red-emitting quantum dots phosphor replacement, (for search)



Recently, CdSe/ZnS core/shell II-VI quantum dots (QDs) have become excellent candidates for replacing micro-sized powder phosphors in pc-LED backlight lamps because the FWHMs of Cd-based QDs are below 40 nm [14]. For the best results, Cd-based green and red QDs have reached a wider color gamut of more than 115% NTSC in the 1931 CIE xy color space [15]. However, Cd-based QDs are toxic and environmentally harmful. In order to
reduce the use of Cd elements, III-V and I-III-VI2 non-toxic QDs have been extensively investigated as color converters in pc-LEDs with the view to fabricating general lighting instead of backlit devices, because the FWHMs of non-Cd QDs available are significantly
broader (> 40 nm) than those of Cd-based QDs [16–19]. Nevertheless, the non-Cd QDs and Cd-based QDs may become viable alternatives to the rare-earth activated inorganic phosphors
because rare-earth elements are considered critical materials in the market due to their scarcity and cost [19]. Through the significant efforts made by numerous researchers, the widest color
gamut that non-toxic InP/ZnS QDs can reach is ~87% relative to the NTSC standard. In addition, the reliability, photo-/thermo-stability, and longevity remain as important issues from the perspective of acceptance of both Cd-based and non-toxic QDs in pc-LED
technology [20]. The developments of various thick-shelling technologies have attempted to enhance the material reliability of QDs [21]; however, the discovery of new types of
environmentally viable and reliable QDs with narrow FWHMs remains a challenge for “onchip” pc-LED backlights.

.....the non-toxic InP/ZnS QDs color gamut (87%)
https://www.osapublishing.org/view_article.cf...o&org=

......shipment of RG qds may be more impt than some seemed to think