Energy Efficient LEDs For Sustainable Solid
Steve DenBaars Solid State Lighting and Display Center
Materials and ECE Departments University of California, Santa Barbara
Engineering Insights Conference UCSB 2008
Energy Efficient LEDs For Sustainable SolidState Lighting
Steve DenBaars Solid State Lighting and Display Center
Materials and ECE Departments University of California, Santa Barbara
Engineering Insights Conference UCSB 2008
SolidState Lighting and Display Center
• One of the largest University Cleanrooms (13,000 ft2)
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• World Class MOCVD/MBE Facilities – 6 MOCVD Systems, 7 MBE (3 Nitride)
• Optical Test Facilities (LED and Laser)
• Materials Characterization (TEM,SEM,FIB, XPS, AFM, SIMS)
• Package and Lamp (LED and Laser) Assembly and Test
State Lighting and Display Center
One of the largest University Cleanrooms (13,000 ft2)
7 equipment bays
World Class MOCVD/MBE Facilities 6 MOCVD Systems, 7 MBE (3 Nitride)
Optical Test Facilities (LED and Laser)
Materials Characterization (TEM,SEM,FIB, XPS, AFM, SIMS)
Package and Lamp (LED and Laser) Assembly and Test
UC Santa Barbara Solid State Lighting & Display Center Industry Partners
Matsushita Electric Industrial Co., Ltd.
10 Industrial Partners
UC Santa Barbara Solid State Lighting & Display Center Industry Partners
10 Industrial Partners
Solid State Lighting UCSB Contributors (63) Faculty (9) • Prof. Shuji Nakamura • Prof. James Speck • Prof. Umesh Mishra • Prof. Claude Weisbuch • Prof. Evelyn Hu • Prof. Anthony Cheetham • Prof. Chris Van de Walle • Prof. Fred Lange • Prof. Pierre Petroff
Visiting Researchers(8) H. Sato, M. Saito, H. Asamizu, A. Murai, H. Yamada, K. Iso, W. Cheol, F. Diana, H. Hirasawa
Staff & Students(46) Dr. Keller, Dr. Feezel, Dr. Cohen, Dr. Chen, Dr. Choi, Dr. Baker, Dr. Hashimoto, Dr. Appelhans,
Dr. Wu M. Iza, M. Coulter, B. Carrelejo M. Schmidt, A. Tyagi, H. Zhong, C. Moe, N. Fellows, H. Masui, S. Cruz, S. Newman, K.
Vampola, E. Matioli, D. Kamber, E. Letts, A. Getty, R. Farrell, D. Brown, D. Thompson, B. Imer, T. BenYaacov, A. Corrion, M. Tsai, M. Furukawa, N. Fichtenbaum, S. Pimputkar, R. Chung, Z. Jia, A. Hirai, S. Brinkley, A. Tamboli, K. McGroddy, H. Zhong, C. Neufeld
Y. Warner, J. Vasquez, G. Callaway
Solid State Lighting UCSB Contributors (63)
H. Sato, M. Saito, H. Asamizu, A. Murai, H. Yamada, K. Iso, W. Cheol, F. Diana, H. Hirasawa
Dr. Keller, Dr. Feezel, Dr. Cohen, Dr. Chen, Dr. Choi, Dr. Baker, Dr. Hashimoto, Dr. Appelhans,
M. Schmidt, A. Tyagi, H. Zhong, C. Moe, N. Fellows, H. Masui, S. Cruz, S. Newman, K. Vampola, E. Matioli, D. Kamber, E. Letts, A. Getty, R. Farrell, D. Brown, D. Thompson, B.
Yaacov, A. Corrion, M. Tsai, M. Furukawa, N. Fichtenbaum, S. Pimputkar, R. Chung, Z. Jia, A. Hirai, S. Brinkley, A. Tamboli, K. McGroddy, H. Zhong, C. Neufeld
Luminous Efficacy of Various Light Sources
2006
x
Graph taken from www.lampteck.co.uk
LED
Luminous Efficacy of Various Light Sources
Current number for GaN white LED at UCSB is 160lm/W ucsb chip
First white LEDs were only 5lm/W at 20mA (1995)
LED
What is an LED?
Blue LED
L.E.D.= Light Emitting Diode (Runs on 3.2V DC Power)
What is an LED?
LED produces light by combining Positive and negative charges inside Gallium nitride crystal
L.E.D.= Light Emitting Diode (Runs on 3.2V DC Power)
Ban the Light Bulb? • “Ban the Incandescent Light Bulb” gaining momentum • California Legislator Lloyd Levine introduces bill to ban the incandescent
light bulb – February 1, 2007 • Australia passes legislation to ban the
light bulb by 2010 – February 21, 2007 • EU to ban light bulbs – March 9, 2007 • United States ????
Ban the Light Bulb? “Ban the Incandescent Light Bulb” gaining momentum California Legislator Lloyd Levine introduces bill to ban the incandescent
Australia passes legislation to ban the February 21, 2007
March 9, 2007
CFL
LED
Lighting: Large Electricity Consumption
Lighting is single biggest users of Electricity
•
•
•
Lighting: Large Electricity Consumption
Lighting is single biggest users of Electricity
Incandescent Light Bulb 14% efficient
Fluorescent – 1525% efficient
LED 2560% efficient (90% theoretical)
The Advantage of LED Lighting Long life – lifetimes can exceed 100,000 hours as compared to 1,000 hrs for tungsten bulbs.
Robustness – no moving parts, no glass, no filaments.
Size – typical package is only 5 mm in diameter.
Energy efficiency – up to 90% less energy used translates into smaller power supply.
Nontoxicity – no mercury.
Versatility – available in a variety of colors; can be pulsed.
Cool – less heat radiation than HID or incandescent
The Advantage of LED Lighting lifetimes can exceed 100,000 hours as compared to 1,000 hrs
no moving parts, no glass, no filaments.
typical package is only 5 mm in diameter.
up to 90% less energy used
available in a variety of colors; can be pulsed.
less heat radiation than HID or incandescent
White Light White Light
Substrate
UV GaN LED
Blue GaN LED
Green GaN LED
Red GaAs LED
White Light White Light
MultiChip, RGB best efficiency highest cost
UV + Phosphors best CRI,color uniformity low cost improved reliability
3 Methods of Generating White LEDs
UV GaN LED
UV light
RGB Light
White Light White Light
Substrate
Blue GaN LED
Blue Light
Green, Red phosphors
UV + Phosphors best CRI,color
improved reliability
Blue + Phosphors lowest cost 30lm/W >90%market share
3 Methods of Generating White LEDs
“The Promise” Energy Usage Comparison
0
10
20
30
40
50
60
Light Source
“Best” White LED and Compact Fluorescent vs. 60Watt Light Bulb Comparison
Pow
er Used (W
atts)
LEDs Save 53Watts
“The Promise” Energy Usage Comparison
Light Source
60W Bulb
Compact Fluor. LED
“Best” White LED and Compact Fluorescent vs. 60Watt Light Bulb Comparison
Global Warming/Energy Savings Potential of LEDs
If a 150 lm/Watt Solid State White LED source were developed, then in the United States alone:
• We would realize $115 Billion cum. Savings in 2025* • Alleviate the need of 133 new power stations!* • Eliminate 258 million metric tons of Carbon* • Save 273TWh/year in energy**
* “The Promise of Solid State Lighting” OIDA Report , 2001, http://www.netl.doe.gov/ssl/PDFs/oida_led **A. D. Little, “Energy Savings Potential of SSL” Report for Dept. of Energy, http://www.eere.energy.gov/buildings/info/documents/pdfs/ssl_final_report3.pdf
Global Warming/Energy Savings Potential of LEDs
If a 150 lm/Watt Solid State White LED source were developed,
We would realize $115 Billion cum. Savings in 2025* Alleviate the need of 133 new power stations!* Eliminate 258 million metric tons of Carbon* Save 273TWh/year in energy**
* “The Promise of Solid State Lighting” OIDA Report , 2001, http://www.netl.doe.gov/ssl/PDFs/oida_ledoled_rpt.pdf **A. D. Little, “Energy Savings Potential of SSL” Report for Dept. of Energy, http://www.eere.energy.gov/buildings/info/documents/pdfs/ssl_final_report3.pdf
Light Extraction Eff.
Conversion Efficiency
Key Materials Technologies for Energy Efficient White LED
ZnO megacone
Photonic crystal
New phosphors
SLEO low defect
Internal Q. Efficiency
Electrical Efficiency
Key Materials Technologies for Energy Efficient White LED
Semi,nonpolar
New phosphors Contacts, semipolar
New ZnO
Summary of Nonpolar/Semipolar LEDs • Nonpolar/semipolar LEDs is close to c
0%
10%
20%
30%
40%
50%
60%
350 450 Peak Wavelength (nm)
External Quantum
Efficiency
In x Ga 1x N
UV
Cplane
Semipolar
NonPolar UCSB
UCSB 2006
Summary of Nonpolar/Semipolar LEDs Nonpolar/semipolar LEDs is close to cplane EQE
550 650 Peak Wavelength (nm)
(Al x Ga 1x ) .52 In .48 P Polar UCSB
IWN 2006 by Nichia
UCSB 2006
Motivation – Polarization Effects
Spontaneous and piezoelectric polarization cause: 1. band bending 2. charge separation in QW
• Emission red shift • Low recombination efficiency • High threshold current
Growth on nonpolar GaN will solve these problems
Polarization Effects
Historical Evolution of Nonpolar/Semipolar LEDs at UCSB
0
10
20
30
40
50
2001 2002 2003 2004 Year
EQE (%
) • Improved output power and EQE in
Historical Evolution of Nonpolar/Semipolar LEDs at UCSB
2005 2006 2007 2008 Year
41% EQE
Improved output power and EQE in mLEDs.
Current LED Applications
Streetlights
Cell Phone (Nokia)
Traffic signals (Gelcore)
TVs (LED DLP tm
(samsung)
Current LED Applications
tm )
Large Displays (NASDAQ)
Automotive
Laser TV
Mitsubishi "Laser TV" with Arasor and Novalux components (left) and Plasma (right)
Laser TV
Mitsubishi "Laser TV" with Arasor and Novalux components (left) and Plasma (right)
Future SSL Displays Pocket Projector/Cell Phone
Prototype from Novalux using frequency double lasers
Future SSL Displays Pocket Projector/Cell Phone
Prototype from Novalux using frequency double lasers
Solar(Photovoltaics) + LED (Off
“In the few months we have had the White LED lamps the improvement in the children’s academic performance has been absolutely remarkable” Headmaster, Mubarak Village, Pakistan June 2004
www.lutw.org
•Kerosene lighting and firewood are used by 1/3 of the world; they cause countless fires and are very inefficient
•The average villager spends 10 annual income on kerosene.
•LED Lighting costs much less on an annual basis and payback period is just 6 months.
•LED Lighting /Solar Cell Off
www.lutw.org
Light Up The World Foundation
Solar(Photovoltaics) + LED (Offgrid)
“In the few months we have had the White LED lamps the improvement in the children’s academic performance has
Headmaster, Mubarak Village, Pakistan June 2004
Kerosene lighting and firewood are used by 1/3 of the world; they cause countless fires and are very inefficient (0.03 lm/watt).
The average villager spends 1025% of their annual income on kerosene.
LED Lighting costs much less on an annual basis and payback period is just 6 months.
LED Lighting /Solar Cell OffGrid
Light Up The World Foundation
Air/Water Purification
• Fruit and Vegetable Storage Life Extended 1 week • Water Purication: UV LED to kill bacteria
Mitsubishi Refrigerator MRW55H, UV LED 375 nm, 590 nm
Air/Water Purification
Fruit and Vegetable Storage Life Extended 1 week Water Purication: UV LED to kill bacteria
(Credit: HydroPhoton Inc.)
CONCLUSION • R&D Level LED Single lamp efficacy (150lm/W) now exceeds CFL, but:
• Commercial based LED Lamp Fixtures are much lower 71 LPW due to several factors that need further research and development in – Fixture Efficiency – Heat Sinking – Scale up to Mass production
• Stay Tuned….
CONCLUSION R&D Level LED Single lamp efficacy (150lm/W) now
Commercial based LED Lamp Fixtures are much lower 71 LPW due to several factors that need further research