• Home
• Why SSL
• LED Basics
• Using LEDs
• R&D Challenges
• Market Challenges
• Standards

R&D Challenges

This section discusses research and development challenges associated with solid-state lighting, including both light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs). For more details, see Resources at right.

Like any new technology, solid-state lighting must demonstrate a compelling value to buyers before it begins to win sizeable market share from the incumbent technologies it will replace. Over the past decade, research and development have yielded impressive improvements in the cost, color performance, light output, efficacy, reliability, lifetime, and manufacturability of SSL products. Looking at the costs of LED packages specifically, the rate of decline in dollars per kilolumen has been around 25% per year since 2005. As a result, some LED lighting products have become competitive with their conventional counterparts in the marketplace for certain applications.

Despite the rapid pace of its development, solid-state lighting has not yet come close to achieving its full potential. Significant work remains to be done to further improve performance and reduce costs.

• Light-emitting diodes (LEDs)—semi-conducting devices that produce light when an electrical current flows through them—are based on inorganic (non-carbon-based) materials. Optimizing efficiency in LED lighting will hinge on ongoing improvements to materials and light extraction techniques. Researchers also are pursuing enhanced reliability in LED lighting, encompassing not only the LED itself but the luminaire and electronic components as well. Other research challenges include improving power supply and driver performance, and enhancing color quality and consistency.
• Organic light-emitting diodes (OLEDs) are based on organic (carbon-based) materials. Unlike LEDs, which are small point sources, OLEDs are made in sheets that provide a diffuse-area light source. While developing rapidly, OLED technology is less mature than LED technology and still some years away from becoming a practical general illumination source. Innovations are needed on multiple fronts to increase the efficiency, lifetime, and output of OLED devices, and manufacturing infrastructure investments will be essential to transitioning OLED products from the prototype stage to commercial viability.

DOE's SSL R&D activities spur advances in efficacy and performance of LED and OLED technologies that might not otherwise be achieved without DOE funding. The three-pronged R&D program addresses:

• Core Technology Research, focusing on applied research for technology development, with particular emphasis on meeting efficiency, performance, and cost targets;
• Product Development, using the knowledge gained from basic or applied research to develop or improve commercially viable materials, devices, or systems; and
• Manufacturing Support, aimed at accelerating SSL technology adoption and encouraging a role for U.S.-based production through manufacturing improvements that reduce costs and enhance product quality.

Together, these three efforts target making SSL competitive with conventional lighting technologies on a first-cost basis and creating a U.S.-led market for high-efficiency light sources.

Current Projects

Since 2003, DOE has worked with more than 200 research partners to accelerate SSL advances as well as to drive the technology from lab to market, resulting in over 100 patent applications. Areas of investigation in SSL R&D are chosen with great care, as are the partners and projects, which DOE selects based on such factors as energy savings potential, likelihood of success, and alignment with the DOE SSL R&D Multi-Year Program Plan and SSL Manufacturing R&D Roadmap.

To learn more, view the current R&D portfolio and R&D highlights.

Shaping the SSL R&D Agenda

Two documents guide the DOE SSL R&D Program: the DOE SSL R&D Multi-Year Program Plan and the SSL Manufacturing Roadmap. All funding opportunity announcements (FOAs) and project selections align with these two documents, which are updated annually in collaboration with industry partners. Priority tasks of the MYPP and Roadmap are broken out separately for LEDs and OLEDs.

Industry input on the MYPP and Roadmap is sought annually. Proposed lists of updates are developed at focused industry roundtables and then vetted at annual DOE workshops with larger groups of participants. DOE workshops bring together America's best and brightest scientists focused on solid-state lighting research and development advances, strategies, and ideas. These exchanges inform not only DOE-sponsored R&D, but also research agendas in academia and industry.

Competitive solicitations for R&D funding of promising SSL technologies are issued annually. R&D partners and projects are selected based on factors such as energy savings potential, likelihood of success, and alignment with the MYPP and Roadmap.

Early 1960s to late 1990s: The Monochrome Era LEDs first appeared on the lighting scene in the early 1960s, in the form of red diodes. Pale yellows and greens followed. As red LEDs improved, they began appearing in products as indicator lights and in some of the first pocket calculators. The appearance of blue LEDs in the 1990s led to the first white LEDs, which were made by coating blue LEDs with phosphor. Shortly thereafter, green, blue, and red LEDs were combined to produce white light. With the availability of white light, LEDs could now be designed for general lighting, but to realize the full potential of LEDs, vast efficiency improvement was needed. 2000-2010: LED General Illumination In 2000, DOE and private industry partners pushed white LED technology forward with the intention to develop a high-efficiency LED packaged device. At the start, white LED devices were no more efficient than the incandescent bulb. By 2010, a comparable warm white LED replacement lamp with good color rendering showed a steady-state efficacy of about 62 lumens per watt (lm/W) compared to about 13 lm/W for incandescent: about three to four times more efficient, with similar quality warm light. In terms of packaged LED components, lab efficacies of 200 lm/W were demonstrated in 2010, with commercially available cool white devices producing efficacies as high as 132 lm/W. 2011-2015: The Future of LED General Lighting Researchers believe the maximum achievable efficacy for packaged LED devices is around 250 lm/W, depending on the color temperature. Rapid progress will continue as the DOE and industry partnership pushes this technology to its efficiency limit, expected to be reached by about 2020. Properly designed LED luminaires could achieve efficacies over 200 lm/W, or up to 15 times that of incandescent lighting with improvements in luminaire components that can add to loss of light and power.  LEDs, although expensive now, will continue to fall in price as new and better ways to package and manufacture them are perfected. 2013-2018: The Promise of OLED General Lighting While LEDs act as concentrated sources of bright light, OLEDs can be configured as larger-area, more diffuse light sources. These may be more practical for general ambient lighting or, if on a flexible base material, can be shaped and integrated more tightly into architectural designs. Improvements in OLED light output continue, with reports of up to 68 lm/W for small "panel" devices that can be combined into luminaire products. While OLED efficiencies are on track to catch up with LEDs over the next several years, other challenges remain, including making larger panels of about 200 cm2, and addressing environmental stability, lifetime, and, above all, cost and manufacturability. As soon as these challenges are overcome, OLED products will appear on the market, to compete with incumbent lighting.