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Partnership for Solid-State Lighting: Report of a Workshop Panel I: National Goals and Laboratory Contributions INTRODUCTION David Goldston House Science Committee Mr. Goldston introduced the members of the first panel and praised the topic of the day as being relevant both to current energy issues and to the ongoing debate about the nature of federal science activity. ENERGY SAVING OPPORTUNITIES IN SOLID-STATE LIGHTING Mark Ginsberg Department of Energy Dr. Ginsberg called the topic of the symposium as “an exciting one, with the potential to not only advance the nation’s technical know-how but also to alleviate pressure on the energy crisis and to create high-tech jobs here at home—a nice combination.” He cautioned, however, that the development of this technology would require considerable talent and many partners. “The advancement of solid-state lighting is a task far too big for [our department] to do alone,” he said. Dr. Ginsberg heads the Office of Building Technology, State and Community Programs, known as BTS, at the Department of Energy (DOE). Its mission is to work in cooperation with industry and other governments to develop, promote, and integrate energy technologies and practices to make buildings more efficient
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Partnership for Solid-State Lighting: Report of a Workshop and affordable. BTS was created to help manage and serve as a catalyst for positive change in the building sector. As part of this mandate BTS has studied lighting sources and systems over a long period and, through that work and through industry-driven roadmaps, it has helped solid-state lighting emerge as a promising technology and a candidate for accelerated development. Solid-state lighting has already demonstrated its superior energy efficiency and longevity in selected niche applications, and Dr. Ginsberg said that the symposium would help to extend this progress through the exchange of ideas. The Solid-State Revolution He offered a brief history of the solid-state revolution. The first chapter produced the transistor radio in the 1940s and 1950s, bringing worldwide access to information and entertainment. A more recent development was the possibility of replacing cathode-ray television sets and bulky computer monitors with highly efficient, high-quality solid-state flat screens. Even better screens are promised by organic light emitting diodes, or OLEDs, for which prototypes are already available. In both substitutions each solid-state replacement has proven to have higher quality, reliability, and energy efficiency than its predecessor. Solid-State Lighting Solid-state lighting began with inorganic LEDs that were first known as signal lights, employed for on-off applications in electronic devices and more recently in traffic signals and exit signs. BTS believes that sufficient R&D can overcome technical barriers and move solid-state lighting into the white-light market to compete both with Edison’s incandescent bulbs and with fluorescent technologies. Just a few years ago it was assumed that LEDs would never have such wide application because of their high cost and limited color. While that debate went on, a quiet revolution led to color breakthroughs and the NASDAQ sign in Times Square with its 16.8 million LEDs. A more recent technology was initially developed by Eastman Kodak and its partners: organic LEDs, or OLEDs, which may eventually replace the computer screen and computer monitors we have today. OLEDs are already being used in mobile phones and car radios. If research continues to be successful, these OLED displays will eventually be incorporated into such building elements as ceiling tile and other home and office applications described earlier by Dr. Kennedy. These systems may also employ frequencies and signals that are invisible to the human eye, enabling our computer and communication networks to run without wires in the office of the future. In addition to general illumination and the specific uses for LEDs and OLEDs
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Partnership for Solid-State Lighting: Report of a Workshop already described, solid-state lighting may offer benefits to other subgroups of optoelectronics. One is vertical-cavity surface-emitting lasers, or VCSELs, which have the potential to run the fiber-optic backbone of the Internet and perform medical and scientific research. Energy Savings Dr. Ginsberg reviewed the energy-saving potential of solid-state lighting. Total energy consumption in the United States in 1998 was almost 95 quadrillion BTUs, or quads. About a third of this energy, or 35.6 quads, was used to generate the electricity used in all commercial, industrial, and residential applications, including lighting. Across all sectors the national primary energy consumption dedicated to lighting is approximately 6.3 quads, or nearly 18 percent of the total electricity used in buildings. The commercial sector uses 54 percent of this, followed by the residential (26 percent) and industrial (14 percent) sectors. Lighting is also a key contributor to peak electricity demand and increases the internal heat load of buildings. For each of the four sectors BTS has targeted those with biggest electricity consumption—primarily residential incandescent and commercial incandescent and fluorescent lighting—as the key areas where solid state will have to be competitive to achieve significant energy savings. BTS had also estimated how much of the 6.3 quads of energy used for lighting might be replaced. The study considered three scenarios: (1) the base case; (2) a case in which technology breakthroughs are achieved by limited investment and innovation but the cost of manufacturing remains high; and (3) a case in which investment achieves not only technical breakthroughs but also dramatic price reductions to about 50 cents per kilolumen of light. Dr. Ginsberg presented a bar chart reflecting this analysis (See Figure 1). The first set of the three bars showed the reduction in quads of energy for use by lighting in 2020, which ranged from 0.15 quads for the base case to 2.6 quads for the price-breakthrough case. The second set of bars showed cumulative energy savings achieved between now and 2020, with the potential under the price-break-through scenario to save nearly 14 quads of electricity, the equivalent of $93 billion in the United States. A Roadmap for Lighting DOE recently sponsored five meetings to develop an interest in white light from solid-state lighting sources. In accordance with DOE’s Vision 2020 roadmap, which was developed with industry, these meetings drew on key stake-holders from industry, academia, and the national labs. The invited experts, some of whom were attending the current symposium, identified the technical barriers that needed to be addressed. At the same time they concluded that there are no
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Partnership for Solid-State Lighting: Report of a Workshop FIGURE 1 Energy Savings Projection. known barriers to prevent solid-state lighting from becoming the primary source of general illumination lighting. In other words, no new laws of nature or theoretical breakthroughs are required to achieve this goal. A Time for Acceleration From this evidence Dr. Ginsberg said that “it’s compelling that we should accelerate R&D in solid-state lighting.” He summarized the following points in favor of such an acceleration: U.S. researchers pioneered the invention of solid-state lighting. Solid-state systems are the most efficient way to turn electrons into photons. It represents a significant shift in design, products, and lighting systems. It creates the opportunity to capture over 2 quads of energy by 2020. Solid state is potentially more environmentally benign than current technologies by avoiding the mercury contamination of landfills from fluorescent tubes. LED technology development has reached the time when it is possible to focus research on achieving desirable price and performance targets.
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Partnership for Solid-State Lighting: Report of a Workshop An American Solid-State Lighting Initiative The leap from incandescent bulbs to LEDs, he said, is potentially as great as the leap a century ago from open flame to incandescent bulbs. Completing that leap, however, depends on a national partnership between government, industry, and academia—an American solid-state lighting initiative. Other countries, where national governments play a major role in coordinating and funding the risky, long-term research have already launched such partnerships. Industry by itself is constrained to focus its R&D resources on the immediate markets of signaling and display; it has few resources available for long-term research. That research must be supported by government, he said, and carried out in government labs and universities. With an American solid-state lighting initiative, he said, this country has the opportunity to create a new business sector, reduce national electricity consumption, and allow U.S. technical expertise to commercialize LED lighting technology first. COMMITTEE ON OPTICAL SCIENCE AND ENGINEERING: STUDY RECOMMENDATIONS David Attwood Lawrence Berkeley National Laboratory Dr. Attwood said he would give a brief report on the work of the Committee on Optical Science and Engineering (COSE).2 The panel has held numerous hearings and has issued both findings and recommendations on the subjects of optical sensing, lighting, and energy. He summarized recent developments in solid-state lighting sources and said that they “now offer a dramatic new set of options,” including LEDs that have the potential to be up to 10 times as efficient as standard light bulbs, reducing consumer electricity bills by tens of billions of dollars in the United States. This would bring less pollution, a need to build fewer power plants, and the opportunity to use those monies for other goals. The COSE Report In its 1998 report3 the committee recommended a national initiative that would include such organizations as DOE, the Environmental Protection Agency, the Electric Power Research Institute, and the National Electrical Manufacturers 2 COSE was formed by the National Research Council in 1995 and is sponsored by the Board on Physics and Astronomy and the National Materials Advisory Board. Its members are drawn from academia, industry, and government. 3 National Research Council, Harnessing Light: Optical Science and Engineering for the 21st Century, Washington, D.C.: National Academy Press, 1998.
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Partnership for Solid-State Lighting: Report of a Workshop Association. The primary objective of the initiative would be to coordinate efforts to enhance the efficiency and efficacy of new lighting sources and delivery systems, with the goal of reducing U.S. consumption of electricity for lighting by a factor of two over the next decade, at a savings of $10 to $20 billion. He also referred to the more recent estimates by Mr. Ginsberg (see above). He summarized some of the benefits of LEDs, including high efficiency, energy conservation, and low-temperature operation. He also cited the need for materials and manufacturing research, much of it multidisciplinary, to improve and capitalize on these benefits. Much interdisciplinary research remains to be done in the fields of organic and polymer electrochemistry, including the study of the injection and transport of charged species in the medium. Features of a Lighting Partnership To accomplish this work, he said, requires a partnership for an initiative in lighting. The COSE report identified the technical challenges, recommended an organizational structure, and outlined the importance of roadmaps to specify the needed steps. It also described key features of such an initiative: The key partners: industrial labs, national labs, and universities; Primary support needs: industrial and government funding, and creation of a broad-based infrastructure; The means to construct the initiative: contracts among private firms and CRADAs between government and the private sector; and Legal issues: intellectual property, ownership, and licensing. An Analogous Effort in Extreme Ultraviolet He said that the semiconductor industry is participating in a similar initiative to develop extreme ultraviolet lithography. The industry has needed help in developing new, complex techniques to print computer chips, and formed a partnership with the federal government through a CRADA including six companies and three national laboratories. Thus, an industry-driven initiative was created with the goal of extreme ultraviolet capability during the years 2007 and beyond. The technology has emerged out of university and then national laboratory research, and involves three national labs and six semiconductor companies. Dr. Attwood concluded by saying he would discuss this partnership more fully later in the symposium.
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Partnership for Solid-State Lighting: Report of a Workshop NATIONAL SECURITY IMPLICATIONS Al Romig Sandia National Laboratories Dr. Romig turned from the technical description of solid-state lighting to the national security implications of optoelectronics. This subject extends beyond lighting issues, he said, to the base materials that make this technology possible, and it has many applications that go beyond lighting. Advantages of Optoelectronics for Defense He said that Sandia National Laboratories serve as a national security facility, and that about half of Sandia’s budget is for nuclear deterrence activity. He noted that Sandia was first drawn to the investigation of optical techniques several decades ago because of the many advantages for weapons systems. There are several reasons for this: Solid-state optoelectronic systems containing fiber optic materials are easier to protect from lightning and static discharge than conventional electronic systems and they allow for simpler and more cost-effective designs. In addition, solid-state electronic and optoelectronic systems have also proven their worth in controlling and monitoring weapons of mass destruction because they are safe, secure, and reliable. They are also used in the Division of Energy and Critical Infrastructures for energy, transportation, and information, as well as in “architectural surety” and smart weapons. Advantages of Integrated Microsystems One enabling technology now emerging is integrated microsystems, which are particularly cost effective. Integrated microsystems combine the abilities to sense activity, process and store data, take mechanical action, and communicate, either optically or through RF technologies. They allow systems that used to require large spaces or boxes to be miniaturized so effectively that they fit on a single chip. A number of applications using materials that are useful for lighting are also playing a major role in microsystems. The next leap in microsystem function, he said, will involve more than just packing additional transistors on a chip. It will involve building new microscopic structures alongside the transistors and giving chips the ability to “think, sense, act, and communicate.” Energy as a National Security Issue Solid-state lighting will contribute to national security by increasing energy efficiency, thus decreasing dependence on foreign energy sources. The potential
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Partnership for Solid-State Lighting: Report of a Workshop energy value for solid-state lighting is striking when compared to the inefficiencies of traditional sources. The average efficiency of incandescent bulbs in converting electrical to optical energy is 5 to 6 percent; of fluorescent lights, around 25 percent. Sandia also estimates that solid-state lighting may be able to accomplish the following by the year 2025: Decrease by 10 percent the total global consumption of electricity; Free over 125 GW of global generating capacity at $50 billion in construction costs; and Reduce global carbon emissions by 200 million tons per year. He emphasized that the availability of energy is a major national security concern, reminding his audience that “we have gone to war over energy in the case of the Gulf War.” Sandia’s Solid-State Programs He reviewed some of the solid-state devices that have been built at Sandia, including LEDs and mini-lasers: About four years ago Sandia demonstrated a vertical-cavity surface-emitting laser (VCSEL) that operated at 60-percent efficiency. Many military applications of high-frequency light have inspired work not only in the area of phosphides but also a “whole potpourri of things that have driven activities at Sandia now for almost 20 years.” Nitride materials will eventually play a large role in the lighting initiative and are also important for national security. The Role of Nitrides He elaborated on three main areas in which nitrides figure in major technologies: Chemical and biological weapons sensing. One can use fluorescencebased chem-bio sensors to detect the presence of such weapons. LED-induced fluorescence can be detected from UO2-doped glass in chemical weapons. Ultraviolet LED-induced fluorescence can also be used to detect biological agents. For example, light in a variety of wavelengths might be used to detect fluorescence from E. coli bacteria as well as to detect anthrax spores; a laser of any size can produce such effects, but Sandia has used primarily very small lasers based on solid-state technology, typically a VCSEL. Such a laser can be put into a micro-robot about the size of a quarter. Detection of missile launches. In sensing weapons of mass destruction it
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Partnership for Solid-State Lighting: Report of a Workshop is helpful that little solar radiation of wavelengths around 250 nm reaches Earth. This is a wavelength where substantial thermal emissions from the plumes of missile launches can be detected. One can build devices based on nitrides that are sensitive to those wavelengths, allowing airborne or ground-based surveillance platforms to search for missile launches. The miniaturization that is possible with solid-state devices makes it possible to fly them on very small platforms. Devices of these wavelengths can also be used for high-frequency radar imaging and high-efficiency, low-weight satellite communications. Synthetic aperture radar. Sandia invented synthetic aperture radar (SAR), which functions well at night and through clouds. The first SARs, built in the 1990s, weighed several hundred pounds and had to be carried aboard Twin Otter aircraft. Miniaturization with solid-state devices has so decreased the size of SARs that they can now be flown on an unmanned vehicle called a Lynx, which is about 12 feet long. In the near future the weight of SARs will be reduced by another order of magnitude, so that SARs will fly on much smaller and cheaper and more elusive unmanned vehicles. Small size also has the benefits of low power, high gain, and low noise. A Summary of Advantages Dr. Romig summarized the usefulness of optoelectronics in defensive applications under four headings. In terms of white light he cited the potential energy efficiency of LEDs, recognizing that the usage and availability of energy is itself an issue that can be destabilizing. A benefit of energy efficiency is that it implies fewer CO2 emissions and less global warming. Ultraviolet-based optoelectronics bring extensive opportunities in several key defensive areas, such as sensing the presence of chemical, radiological, and biological weapons of mass destruction and carrying them on ever smaller airborne detector platforms. An additional capacity is being able to scan for missile launches. High-power, high-temperature, solid-state electronics can be used in applications like synthetic aperture radar for decoying, jamming, and other functions. He concluded by noting that optoelectronics also fit well with Sandia’s longheld objective of developing sensors that are resistant to ionizing radiation. This is necessary to monitor the nation’s nuclear stockpile for radiation leakage. The physical properties of optoelectronics also suit them to many non-defense applications in which high-radiation or high-temperature conditions are hazardous to humans.
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Partnership for Solid-State Lighting: Report of a Workshop Thus, his laboratory has found other dual drivers for optoelectronics, where uses may find applications both in defense and in the commercial marketplace. MANUFACTURING INFRASTRUCTURE AND METROLOGY FOR LIGHTING Karen Brown National Institute of Standards and Technology The Role of NIST Dr. Brown, acting Director and Deputy Director of the National Institute of Standards and Technology (NIST), emphasized that metrology is a critical part of being able to bring solid-state lighting to its full potential in the real world. She said that the mission of NIST and its 3,200 employees is “to work with industry to develop applied technology measurements and standards,” and that the needs and potential value of solid-state lighting fit this mission well. The institute has a $700 million budget; $300 million of this goes to its laboratories, which study such subjects as building and fire research, physics, information technology, chemical science and technology, and materials science. NIST is applying a wide range of skills to solid-state lighting today, and a key enabler of that is metrology services, or “the ability to measure the output of light sources and the ability to develop standards to make this technology a reality.” She described a similar effort by NIST to promote the semiconductor sector by supporting development of the lithography process. NIST can provide such complex services as light-scattering measurement, optical properties, and materials data. Some of these data help describe the index of refraction of materials, laser wavelength standards, laser power and energy, line-width measurement standards, and artifacts that can be used to calibrate functions as part of the manufacturing process. In other words, it helps with a spectrum of technical needs, from fundamental materials properties to manufacturing properties, according to the evolving needs of industry. Dr. Brown agreed with the conclusion that LED applications have been expanding rapidly, especially during the last 10 years. She noted that the NASDAQ sign is an example of what can happen in the future: “It’s not a dim little thing; it lights up Times Square.” The first companies that manufacture high-efficiency white LEDs with good color rendering, she said, have a huge opportunity to capture a market that is not only large but also new in many ways.4 4 Some workshop participants pointed out that companies that are the first to manufacture high efficiency white LEDs with good color rendering will capture a huge market opportunity. Accurate color rendering is extremely significant for the widespread acceptance and application of solid-state lighting in the general illumination market.
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Partnership for Solid-State Lighting: Report of a Workshop The Need for Better Metrology She referred also to the earlier discussion of the economics of solid-state lighting. To bring down costs, she said, improvements are needed in gallium nitride fabrication, new measurements of process metrology, improved electrical contacts, and improved luminous efficacy, or lumens per watt. To reach any of these goals, industry requires improved measurements and improved materials support. NIST is working in the area of photometric standards for LED measurements and chemical and physical data and measurements for new materials. Industry needs have driven improvements in LED performance measurements. Manufacturers and users of LEDs have found large discrepancies in their measurements, and the particular directionalities and wavelengths of LEDs create a need for a new way of measuring. In response NIST is developing standard LEDs for photometric measurements with the goal of 2-percent accuracy for LEDs at all wavelengths and colors. They are also developing standard LEDs for color measurement. A Lack of Metrics Could Limit LED Development Industry also needs a way to characterize emerging LED materials, such as gallium nitride and related alloys, in order to manufacture blue and green LEDs that are more efficacious at prescribed wavelengths. In particular, NIST is developing non-destructive methods to evaluate defects and their influence on the device properties. This is required to improve the structure and purity of the materials. The lack of methods to measure optical, electrical, and structural properties with nanometer-scale resolution is a primary limiting factor in LED development. One class of techniques being developed for this dimensional scale is nonlinear optical analysis. NIST is also exploring the application of Raman spectroscopy and other methods that are non-contacting, non-destructive, and may be used for real-time process control for manufacturing. Finally, NIST is using electron microscopy and X-ray diffraction to reduce defects produced when gallium nitride LED chips are connected into microelectronic and optoelectronic devices. The laboratory gathers metallurgical data and measures types and concentrations of defects to point the way to the best lowresistance electrical contacts for use with gallium nitride. Partnerships with Industry Dr. Brown emphasized the breadth of the studies under way, both in technological scope and in the variety of participants. In conclusion she stated that the goal of this work is to collaborate effectively with industry to meet the metrology
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Partnership for Solid-State Lighting: Report of a Workshop needs of both manufacturing and research. The program addresses the range of R&D from basic research and development to production and applications of LEDs, as well as a considerable effort to understand human-factor responses to light and understand how light is perceived. DISCUSSION Current Obstacles to LED Development Moderator David Goldston asked the panel to describe the greatest current obstacles to the development of solid-state lighting. He received the following responses: Dr. Ginsberg said that investment is a key, then technical breakthroughs, and finally “the will.” Dr. Attwood emphasized the two major phases of developing any new technology. The first is to develop the technology itself and then demonstrate it through laboratory testing and through, for example, limited uses for space or the military. The second phase, which requires major investments, is to “mature” the technology, strengthen its reliability, and raise manufacturing yields. “Historically,” he said, “95 percent or more of the cost of bringing any technology to the market occurs in the maturation stage.” Dr. Brown emphasized the importance of improved standards and measurements. Before any technology is adopted, manufacturers have to agree on standard metrics to describe how it is produced and quantified. This does not mean there cannot be unique applications, she said, but broad-based acceptance across a range of applications requires standardization, at least in the beginning. Dr. Romig said that more early-stage research was needed to provide leverage. Development of solid-state lighting requires more multidisciplinary research in solid-state electronics and optical tools, optical luminescence, and polymer chemistry research. Funding for these areas has multiple benefits, because they will have applications to optoelectronics beyond lighting. Barriers to Acceptance and Funding Needs Dr. Wessner asked about circumstances during the development of Edison’s incandescent bulb and about the magnitude of financing that would be required for a partnership for solid-state lighting. Dr. Ginsberg replied that Edison invented the incandescent bulb in 1889 but that it did not enter widespread use until the 1920s. Acceptance required new manufacturing techniques and electrifica-
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Partnership for Solid-State Lighting: Report of a Workshop tion of the nation. Other issues were standardization and acceptance of the common bulb and socket, the testing of materials, and the construction of an electrical infrastructure. He said that we can expect quicker adoption today partly because LED innovation is moving rapidly, as exemplified by the NASDAQ sign and the proliferating traffic and exit lights. In response to the question about funding requirements, Dr. Haitz summarized a study he had conducted some 18 months earlier. He estimated that a government-industry partnership would want to spend about a billion dollars over the next 10 years to accelerate solid-state lighting to a significant degree; in other words, each sector would spend about $50 million a year. He said that the industry is approaching the fourth generation of solid-state systems, and that developing each generation had exceeded estimates of cost and complexity by a factor of at least three. The gallium nitride system in particular is “incredibly complicated” and would require considerable hard work. He added that an efficacy of 50 lumens per watt (l/w) is within reach, but that level is inadequate to have a competitive impact on fluorescent lamps. In order to have that impact and to save energy, he said that well over 100 l/w would be needed. “And that’s not going to be done in a slow, evolutionary process. You have to try to develop the breakthroughs.” Solid-State Technology Transfer Dr. Romig was asked how much technology developed for defensive purposes is transferred to the civilian sector. He replied that much of the research done at the base technology level is transferred. An example of this is Sandia’s materials studies of compound semiconductors and high-temperature superconductors. The principal drivers of these studies were the optoelectronics and high-frequency RF applications. The fact that these phenomena now have applications in the realm of lighting is partly a result of learning how to create useful devices based on those materials. He also explained that moving a technology into the marketplace benefits the national lab where it was born. “This is the way I think it’s supposed to work,” he said, “where basic work with defense applications works its way into the marketplace, gets exercised, developed, and matured, and then fed back into our defense systems.”
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