04/30/2012

LED Efficiency Droop

 
More efficient LED lighting options may be on the way for building owners and facility managers.

This is a schematic of the transparent LED packaging design (left) and a working blue LED using the design (right). Credit: Yuji Zhao, University of California Santa Barbara

As many facility managers and building owners are aware, LEDs seem to reach a point where more electricity no longer imparts the same kick and productivity levels-off.  But there may be some very interesting developments on the way that will lead toward more affordable and efficient LED options.  Researchers from California and Japan have devised a new design for green and blue LEDs that avoid much of this LED efficiency droop.

By changing the orientation of the crystal structure in semiconductor films, the team created LEDs with high efficiency and extremely low droop. Droop, which is a dramatic drop in efficiency at high currents, is one of the main problems limiting the growth of the solid-state lighting market.

Blue and green LEDs provide the essential hues that blend with other wavelengths to give us the familiar white light we expect from household bulbs. These highly prized colors, however, have been among the hardest to engineer and the "droopiest" of the LEDs.

"We believe this technology could be a big breakthrough and has the potential to change the future of lighting," says Yuji Zhao, a graduate student at the Solid State Lighting and Energy Center at the University of California Santa Barbara (UCSB) and one of the lead researchers on the team.

LED chips are made from layers of doped semiconductors sandwiched together. When a voltage is applied across the layers, electrons and holes (an absence of electrons) migrate toward an area of the LED called the active layer, where they combine, begetting a photon in the process. In most commercially available blue LEDs, the crystals that make up the semiconductor layers are grown in a flat orientation called the c-plane. This traditional orientation of the crystals, however, may create electrical fields that interfere with the reunion of the electrons and holes.

The UCSB researchers' LEDs have non-traditional, tilted crystal orientations that lessen the effect of the field, and exhibit some of the lowest reported measures of droop. Using this approach the team was also able to fabricate LED chips that are smaller than standard commercial LEDs, which could cut down on manufacturing costs.

 

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Need portable cooling?

Rent or buy spot coolers from full-service locations nationwide. On call “24/7”. Primary, supplemental or emergency cooling. Atlas Sales & Rentals, Inc., or call (800) 972-6600.

Click here for more info


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.

Yaskawa drives offer quality performance for air handlers and cooling towers on the roof to secondary chilled water pumps in the basement

Bluebeam® Revu® simplifies digital facilities document management from design review to leveraging as-builts, maintenance manuals and O&Ms submittals.

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.


 
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