Industry News




 

01/18/2013

LED: New Material, New Possibilities?

 
New possibilies for LED lighting may make the technology more applicable to traditional lighting applications.

Heard about FIPEL?  Well, it looks like LED may have new possibilities as well.  LEDs are known for their energy efficiency and durability, but the bluish, cold light of current white LEDs has precluded their widespread use for indoor lighting.

Now, University of Georgia scientists have fabricated what is thought to be the world's first LED that emits a warm white light using a single light emitting material, or phosphor, with a single emitting center for illumination. The material is described in detail in the current edition of the Nature Publishing Group journal "Light: Science and Applications."

"Right now, white LEDs are mainly used in flashlights and in automotive lamps, but they give off a bluish, cool light that people tend to dislike, especially in indoor lighting," says senior author Zhengwei Pan, an associate professor in the department of physics in the UGA Franklin College of Arts and Sciences and in the College of Engineering. "Our material achieves a warm color temperature while at the same time giving highly accurate color rendition, which is something no single-phosphor-converted LED has ever been shown to do."

Two main variables are used to assess the quality of artificial light, Pan explained. Correlated color temperature measures the coolness or warmth of a light, and temperatures of less than 4,000 kelvins are ideal for indoor lighting.

Correlated color temperatures above 5,000 kelvins, on the other hand, give off the bluish color that white LEDs are known for. The other important measure, color rendition, is the ability of a light source to replicate natural light. A value of more than 80 is ideal for indoor lighting, with lower values resulting in colors that don't seem true to life.

The material that Pan and his colleagues fabricated meets both thresholds, with a correlated color temperature of less than 4,000 kelvins and a color rendering index of 85.

Warm white light can commonly be achieved with a blue LED chip coated with light emitting materials, or phosphors, of different emitting colors to create what are called phosphor-based white LEDs, Pan said. Combining the source materials in an exact ratio can be difficult and costly, however, and the resulting color often varies because each of the source materials responds differently to temperature variations.

"The use of a single phosphor solves the problem of color stability because the color quality doesn't change with increasing temperatures," says lead author Xufan Li, a doctoral student in the College of Engineering.

To create the new phosphor, Pan and his team combine minute quantities of europium oxide with aluminum oxide, barium oxide and graphite powders. They then heat the powdered materials at 1,450 degrees Celsius (2,642 degrees Fahrenheit) in a tube furnace. The vacuum of the furnace pulls the vaporized materials onto a substrate, where they are deposited as a yellow luminescent compound. When the yellow luminescent compound is encapsulated in a bulb and illuminated by a blue LED chip, the result is a warm white light.

Although his team's results are promising, Pan emphasized that there are still hurdles to be overcome before the material is used to light homes, businesses and schools. The efficiency of the new material is much lower than that of today's bluish white LEDs. Scaling the production to an industrial scale will be challenging as well, since even slight variations in temperature and pressure in the phosphor synthesis process result in materials with different luminescent colors.

The new yellow phosphor also has a new lattice structure that has not been reported before. The researchers currently are working to discern how the ions in the compound are arranged in hopes that a better understanding of the compound at an atomic level will allow them to improve its efficiency.

"We still have more work to do," Pan says, "but the color temperature and rendition that we have achieved gives us a very good starting point."

 


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http://news.mehvac.com/hhlaunch/


Visit our website today to learn about the design flexibility of a Morton building and the endless possibilities of partnering with our designBUILD team.


Wood construction is both cost and energy efficient. Check out Morton Buildings and our designBUILD team online today to discover all the benefits of post-frame construction.


When choosing a metal-clad building for your next construction project, consider Morton Buildings, Inc., and their designBUILD team, we’ll make your dream a reality.

We Can Help You Reduce Energy by 30%

Our mission is to help our customers manage their buildings' energy costs, improve reliability, and enhance performance while having a positive impact on the environment.
CLICK HERE to find out how.

Mitsubishi Electric Cooling & Heating’s new H2i R2-Series heat pumps provide year-round comfort, even in extreme climates. With 100% heating capacity down to 0° F outdoor ambient and simultaneous heating and cooling down to -4° F, our hyper-heating systems bring highly responsive multi-zone comfort to your projects, regardless of climate zone.

http://news.mehvac.com/hhlaunch/


 
03/27/2015

Capital ranks #1 in certified buildings.

03/26/2015

New sensor cable technology can detect all types of security breaches.

03/25/2015

Facilities will help cut government GHG emissions by 40%.

03/24/2015

Building sustainability shown to improve tenant happiness.

03/23/2015

New technology to improve the efficiency of wind power systems.

03/20/2015

Reduction of storm activity due to climate change will increase extreme weather.

03/19/2015

Simple ventilation improvements could save over $20,000 per year.

03/18/2015

Efforts to minimize climate change may be more effective than previously thought.

03/17/2015

Researchers develop new approach to create renewable energy.

03/16/2015

Report shows wind becoming cost competitive in more states.

03/13/2015

Study shows “fragrances” may be more than they appear.

03/12/2015

New energy storage configurations could cut costs.

03/11/2015

Program will streamline certification processes, code familiarity.

03/06/2015

Study shows buildings such as hospitals could cut energy use.

03/05/2015

Small and medium-sized buildings will soon have automation options.

03/04/2015

Form will aid lenders in assessing value of sustainable design.

03/03/2015

Expanded choices offer climate-friendly solutions.

03/02/2015

New technology could slash consumption up to 30%.

02/27/2015

Design is low-cost and green while providing more energy storage.

02/26/2015

LEED, IgCC, Standard 189.1 will work in harmony.

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