Lighting Research Center Lighting Research Center

Improving LED Light Output and Efficacy Through SPE™

 


Commercial white LEDs combine a light-emitting semiconductor with a phosphor to produce visible white light. The nature of most phosphors, however, causes more than half of the light, or photons, generated to divert back toward the semiconductor die, where much of it is absorbed and lost. This scattering reduces the LED’s overall light output.

In 2004, LRC researchers developed Scattered Photon Extraction (SPE™), a method to improve the light output and efficacy of white LEDs. The SPE method combines optimally shaped optics and placement of the phosphor away from the die. This configuration allows light traveling back toward the die to escape through the sides of the optics, generating 30 to 60 percent more light output (lumens) and luminous efficacy (lumens per watt of electricity) than typical white LEDs. Moreover, moving the phosphor layer away from the semiconductor die improves LED life.

Since the development of SPE, a number of other LRC studies have used this method to:


This study was part of a larger project funded by the U.S. Department of Energy: High-Efficiency, Nitride-Based Solid-State Lighting

Technical Reports and Publications

Narendran, N., Y. Gu, J.P. Freyssinier-Nova, and Y. Zhu. 2005. Extracting phosphor-scattered photons to improve white LED efficiency. phys. stat. sol. (a) 202 (6): R60-R62.
Journal Abstract

Narendran, N. 2005. Improved performance white LED. Fifth International Conference on Solid State Lighting, Proceedings of SPIE 5941: 45-50.
Full-text PDF pdf logo

Wu, H., N. Narendran, Y. Gu, and A. Bierman. 2007. Improving the performance of mixed-color white LED systems by using scattered photon extraction technique. Seventh International Conference on Solid State Lighting, Proceedings of SPIE 6669: 666905.
Full-text PDF pdf logo

Zhu, Y., and N. Narendran. 2008. Optimizing the performance of remote phosphor LEDs. Journal of Light and Visual Environment 32(2): 115-119.
Full-text PDF pdf logo (Publisher's website)

Zhu, Y., and N. Narendran. 2010. Investigation of remote-phosphor white light-emitting diodes with multi-phosphor layers. Japanese Journal of Applied Physics 49: 100203.
Full-text PDF pdf logo

Zhu, Y., P. Dutta, and N. Narendran. 2010. Post-synthesis annealing effects on SrGa2Se4:Eu2+ phosphors with peak emission wavelength in the green gap. Tenth International Conference on Solid State Lighting, August 1-5, 2010, San Diego, CA, Proceedings of SPIE 7784: 77840P.
Full-text PDF pdf logo


Project Summary Sheets

LED Replacement for Linear Fluorescent Lamps (2013) pdf logo

Designing a Better Recessed Downlight Using SPE Technology (2010) pdf logo

Snap-in LED Module for Outdoor Luminaires (2010) pdf logo

Techniquest to Improve Green Phosphor for Superior White LEDs (2010) pdf logo

White SPE LEDs with Multi-phosphor Layers (2010) pdf logo

Optimizing Remote-phosphor LEDs with Optical Ray-tracing (2009) pdf logo

SPE Technology for Mixed-Color LEDs (2007) pdf logo

'SPE' Method Enhances White LED Light Output (2005) pdf logo


Patent Information

RP Matter
Client Reference
Serial No.
Country
Patent No.
Title
Status
Filing date
Issue Date
RPI-134AU
RPI 858
2005240186
AUSTRALIA
2005240186
HIGH EFFICIENCY LIGHT SOURCE USING SOLID-STATE EMITTER AND DOWN-CONVERSION MATERIAL
ISSUED
5 /5 /2005
5 /19/2011
RPI-134AU1
858
2010257325
AUSTRALIA
2010257325
HIGH EFFICIENCY LIGHT SOURCE USING SOLID-STATE EMITTER AND DOWN-CONVERSION MATERIAL
ISSUED
5 /5 /2005
3 /22/2012
RPI-134CA
RPI 858
2,565,339
CANADA
2,565,339
HIGH EFFICIENCY LIGHT SOURCE USING SOLID-STATE EMITTER AND DOWN-CONVERSION MATERIAL
ISSUED
5 /5 /2005
11/6 /2012
RPI-134CN
RPI 858
200580022283.9
CHINA
ZL0580022283.9
HIGH EFFICIENCY LIGHT SOURCE USING SOLID-STATE EMITTER AND DOWN-CONVERSION MATERIAL
ISSUED
5 /5 /2005
3 /16/2011
RPI-144CN
1043
200780046853.7
CHINA
ZL0780046853.7
LIGHTING SYSTEM USING MULTIPLE COLORED LIGHT-EMITTING SOURCES AND DIFFUSER ELEMENT
ISSUED
5 /29/2007
7 /31/2013
RPI-134JP
RPI 858
2007-511606
JAPAN
5301153
HIGH EFFICIENCY LIGHT SOURCE USING SOLID-STATE EMITTER AND DOWN-CONVERSION MATERIAL
ISSUED
5 /5 /2005
6 /28/2013
RPI-134JP1
996JP1
2011-147334
JAPAN
5301613
HIGH EFFICIENCY LIGHT SOURCE USING SOLID-STATE EMITTER AND DOWN-CONVERSION MATERIAL
ISSUED
5 /5 /2005
6 /28/2013
RPI-134KR
RPI 858
10-2006-7025619
SOUTH KOREA
10-1256919
HIGH EFFICIENCY LIGHT SOURCE USING SOLID-STATE EMITTER AND DOWN-CONVERSION MATERIAL
ISSUED
5 /5 /2005
4 /16/2013
RPI-134KR1
RPI 858
10-2012-7017954
SOUTH KOREA
10-1295561
HIGH EFFICIENCY LIGHT SOURCE USING SOLID-STATE EMITTER AND DOWN-CONVERSION MATERIAL
ISSUED
5 /5 /2005
8 /6 /2013
RPI-134US
RPI 858
10/583,105
UNITED STATES
7,819,549
HIGH EFFICIENCY LIGHT SOURCE USING SOLID STATE EMITTER AND DOWN-CONVERSION MATERIAL
ISSUED
4 /23/2007
10/26/2010
RPI-144US
1043
11/642,089
UNITED STATES
7,837,348
LIGHTING SYSTEM USING MULTIPLE COLORED LIGHT-EMITTING SOURCES AND DIFFUSER ELEMENT
ISSUED
12/20/2006
11/23/2010
RPI-143AU
996
2006262152
AUSTRALIA
2006262152
PACKAGE DESIGN FOR PRODUCING WHITE LIGHT WITH SHORT-WAVELENGTH LEDS AND DOWN-CONVERSION MATERIALS
ISSUED
6 /20/2006
8 /4 /2011
RPI-143US
996
11/795,171
UNITED STATES
7,750,359
PACKAGE DESIGN FOR PRODUCING WHITE LIGHT WITH SHORT-WAVELENGTH LEDS AND DOWN-CONVERSION MATERIALS
ISSUED
7 /12/2007
7 /6 /2010
RPI-146US
1059
11/642,154
UNITED STATES
7,703,942
HIGH-EFFICIENT LIGHT ENGINES USING LIGHT EMITTING DIODES
ISSUED
12/20/2006
4 /27/2010
RPI-145CN
1058
200780042748.6
CHINA
ZL0780042748.6
HIGH-POWER WHITE LEDS AND MANUFACTURING METHOD THEREOF
ISSUED
5 /31/2007
5 /1 /2013
RPI-145US
1058
11/644,815
UNITED STATES
7,889,421
HIGH-POWER WHITE LEDS AND MANUFACTURING METHOD THEREOF
ISSUED
12/22/2006
2 /15/2011
RPI-145US1
1058
12/987,312
UNITED STATES
8,031,393
HIGH-POWER WHITE LEDS AND MANUFACTURING METHOD THEREOF
ISSUED
1 /10/2011
10/4 /2011
RPI-145US2
1058
12/987,315
UNITED STATES
8,164,825
HIGH-POWER WHITE LEDS AND MANUFACTURING METHOD THEREOF
ISSUED
1 /10/2011
4 /24/2012
RPI-156US
1213
13/376,887
UNITED STATES
8,292,468
SOLID STATE LIGHT SOURCE LIGHT BULB
ISSUED
12/8 /2011
10/23/2012
RPI-163US
1154
13/581,861
UNITED STATES
8,646,927
SCATTERED PHOTON EXTRACTION BASED LIGHT FIXTURES
ISSUED
11/6 /2012
2/11/2014
RPI-144US1
 
 
UNITED STATES
8,764,225
Lighting source using solid state emitter and phosphor materials
ISSUED
3/11/11
7/01/14

Sponsors

The Link Foundation, Energy Fellowship Program
United States Department of Energy, Cooperative Agreement No. DE-FC26-01NT41203
University of California at Santa Barbara



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