New Amber LEDs for High-Efficiency Solid-State Lighting
NREL is closing the LED "green gap" with a patent-pending technology that allows for easy manufacturing of low-cost amber LEDs that—when combined with red, green, and blue LEDs—produce brilliant broad-spectrum white light more efficiently than current LEDs. This color-mixing technique enables low-cost, easy-to-manufacture white LEDs with improved luminosity.
This novel device architecture achieves greater efficiencies than current amber LEDs. In addition, the color-mixing approach avoids the energy losses associated with producing white light via conventional (phosphor-converted blue) LEDs.
NREL's game-changing innovation could transform the market for solid-state lighting (SSL) for industry, businesses, and consumers. It also will impact the performance of lasers and photovoltaics.
NREL's amber LED technology is available for license.
NREL's innovative amber LED technology offers significant advantages over current LED techniques, such as:
- Proven efficiency increases: Demonstrates twice the efficiency of current amber LEDs
- Easy manufacturing: Can be fabricated simply on a large scale with existing manufacturing equipment
- Low-cost materials: Uses the same commercially available substrates as for current amber and red LEDs—gallium arsenide (GaAs)
- Better white LEDs: Enables color-mixing white LED architectures that:
- Emit more white light, with an estimated 20% increase in luminosity
- Avoid Stokes-shift energy losses while minimizing photocarrier losses
- Improved color with a color rendering index (CRI) greater than 95.
NREL's amber LED will have a major impact on the trend toward energy efficiency across multiple industries, including:
- Conventional LED-based solid-state lamps
- General lighting, backlighting, etc.
- Industrial and residential lighting
- Components for automotive, medical, consumer electronics, etc.
- Photovoltaics (PVs)
- Ultra-high efficiency solar PVs
- Utility-scale and industrial solar PVs
Many existing solid-state LED technologies are built on monochromatic blue or ultraviolet LEDs. The standard process for converting blue light to white light—known as phosphor conversion for its use of a phosphor coating to extend the blue's wavelength (Stokes shift) over a broad spectrum—significantly reduces the LED's efficiency and reduces luminosity by 20%.
Scientists at NREL have developed a portfolio of novel LED technologies that emit in the green-amber regions of the visible spectrum. These technologies enable color-mixing approaches that incorporate red, green, and blue along with NREL's efficient amber LEDs (RGBA) to create white LED lamps that are highly efficient and avoid the Stokes-shift energy losses.
Given its unprecedented efficiencies, NREL's technology will have a major impact on SSL for industry, businesses, and consumers. Device designs utilizing similar material combinations will also impact the performance of lasers and photovoltaics.
How It Works
Combining amber LEDs with red, green, and blue LEDs achieves RGBA color mixing that yields brilliant white light. This use of amber LEDs is a major achievement, since they historically have demonstrated low efficiency and manufacturing difficulties due to fundamental materials issues.
NREL's innovation utilizes high-bandgap AlxIn1-xP alloys to overcome carrier-loss mechanisms that degrade the performance of phosphide-based amber LEDs. It bridges lattice misfit between the device layers and conventional GaAs substrates via compositionally graded buffer layers. Carrier confinement is achieved via engineered ordered/disordered double heterostructures.
Why It Is Better
NREL's amber LEDs enable high-CRI white light to be produced with significantly greater efficiency and luminosity than was previously possible. Furthermore, NREL's high-efficiency amber LED keeps costs low by using standard manufacturing methods, conventional deposition equipment, and commercially available substrates.
Current amber LED technologies suffer from low efficiencies. NREL's amber LED achieves highly efficient luminescence because its high-bandgap semiconductor prevents inter-valley electron transfer losses at emission wavelengths as low at 570 nanometers. NREL's technique also draws on semiconductor physics to engineer innovative cladding layers that are more effective than the materials and techniques currently used by industry to fabricate amber LEDs.
NREL has applied for U.S. and international patent protection for this portfolio of technologies:
|Technology||U.S. application||International application|
Amber LEDs for Solid-State Lighting: White light with unprecedented efficiencies; commercialization webinar, Dec. 10, 2013.
High Bandgap Phosphide Approaches for LED Applications: A new approach to fabricating green/amber LEDs, U.S. Department of Energy, Energy Innovation Portal
AlxIn1-xP Amber LEDs for Solid-State Lighting, 30-minute webinar:
Amber-green light-emitting diodes using order-disorder AlxIn1-xP heterostructures, published in J. Appl. Phys. 114, 074505 (2013); doi: 10.1063/1.4818477
Growth, microstructure, and luminescent properties of direct-bandgap InAlP on relaxed InGaAs on GaAs substrates, published in J. Appl. Phys. 113, 183518 (2013); doi: 10.1063/1.4804264
Green LEDs for Efficient Lighting: Solar-cell manufacturing techniques could yield LEDs that require 20 percent less energy, published in MIT Technology Review, April 12, 2010
NREL Finds a Way to Give LEDs the Green Light, NREL news feature, April 5, 2010.
NREL is offering this technology suite (ROI-10-64 and ROI-09-36) for license. A webinar described the commercialization process as well as provided detailed information about the technology and its potential markets. Download the slides, watch the webinar (due to technical difficulties, the audio begins on time but the video will not show for approximately 3 minutes), or view the text version.
Learn more about NREL's licensing agreements process.
Other Technology Licensing Opportunities
In addition, NREL has several other related technologies available for licensing that may be of interest:
- Multijunction Solar Cell (PV) Device (international patent application) ref. ROI-09-59
This method for building highly efficient multijunction solar cells relies on using additional layers of other semiconducting materials with intermediate-sized lattice structures that bridge the gap between the disparate-sized semiconductors.
- Growth of Lattice-Matched Semiconductor Layers (U.S. patent applications 20110049520 and 20110147791) ref. ROI-08-34, ROI-08-40, ROI-08-60, ROI-10-37, and ROI-10-44
A portfolio of five core technologies that allow manufacturers to increase yields, reduce costs, and make more efficient semiconductors by better matching the orientations of the semiconductor material to each other and to the substrate.
For more information about NREL's amber LED technology and licensing opportunities, contact , 303-275-3015. Please reference ROI-10-64/ROI-09-36 in your communication.