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US Department of Energy invests $6.4M in LED design
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Magnu-@aol.com
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Aug 25, 2009 18:13 PDT
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_http://www.edn.com/article/CA6685811.html?nid=3351&rid=8615080_
(http://www.edn.com/article/CA6685811.html?nid=3351&rid=8615080)
US Department of Energy invests $6.4M in LED design
The DOE selects four projects that aim to "fill key technology gaps,
provide enabling knowledge or data, and represent a significant advancement in
the SSL technology base."
By Suzanne Deffree, Managing Editor, News -- Electronic News, 8/25/2009
The US Department of Energy (DOE) has announced four selections in response
to its Solid-State Lighting (SSL) Core Technology Research Call that it
will invest $6.4 million in.
The selections aim to "fill key technology gaps, provide enabling knowledge
or data, and represent a significant advancement in the SSL technology
base," the DOE said.
Three of the selected award recipients -- National Renewable Energy
Laboratory, Pacific Northwest National Laboratory, and Sandia National
Laboratories -- will see their projects funded via the American Recovery and
Reinvestment Act at a total $4.6 million.
The National Renewable Energy Laboratory's project, "Lattice mismatched
GaInP alloys for color mixing white light LEDs," seeks to demonstrate the
viability of high bandgap GaInP alloys for synthesis of inexpensive, efficient
Al-free LED devices on conventional GaAs substrates, which emit in the deep
green 560 to 570-nm region of the green gap, or inside the red gap (615 to
625 nm), and for which the LEDs are fabricated using simpler OMVPE growth
and processing techniques conventionally used for GaAs based III-V alloys.
The DOE said that utilization of more efficient emitters, particularly in
the deep green area of the spectrum, will contribute to meeting its
efficiency targets identified for RGB based color mixing LEDs and significantly
lower the cost of such devices.
The Pacific Northwest National Laboratory's project, "Development of
Stable Materials for High-Efficiency Blue OLEDs through Rational Design," aims
to use new materials in a mixed-host system to demonstrate improved lifetime
and efficiency. The DOE said that using new stable materials and improved
OLED device architectures will allow higher device stability and improved
efficiencies in blue OLEDs at currents useful for SSL products, and will
lead to demonstration of highly efficient white OLEDs with longer lifetimes.
And Sandia National Laboratories' project, "Semi-polar GaN Materials
Technology for High IQE Green LEDs," seeks to improve the internal quantum
efficiency (IQE) in green nitride-based LED structures by using semi-polar GaN
planar orientations for InGaN multiple quantum well (MQW) growth. The DOE
said that these semi-polar orientations have the advantage of significantly
reducing the piezoelectric fields that distort the quantum well band
structure and decrease electron-hole overlap. At the end of this program, Sandia
National Laboratories expects MQW active regions at 540 nm with an IQE of
50%, which with an 80% light extraction efficiency should produce LEDs with an
external quantum efficiency of 40%, or twice the estimated current
state-of-the-art.
The last recipient, the US _ARMY_
(http://www.edn.com/hot-topic/49026/military-defense.html) Research Laboratory, will see $1.8 million awarded to
its project via SSL appropriated funds. Its project, "Exploiting Negative
Polarization Charge at n-InGaN/p-GaN Heterointerfaces to Achieve High Power
Green LEDs without Efficiency Droop," aims to exploit the negative
polarization charge at the n-InGaN/p-GaN heterointerface to achieve high-power,
high-efficiency green LEDs without efficiency droop. The DOE said target goals
are 540-nm LEDs with peak IQE of 40% at current densities sufficient to
enable general illumination applications.
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