Skip to content. | Skip to navigation

Personal tools

The Global
Information Hub for
Lighting Technologies
and Design

Sections
Home > Technologies > LEDs & OLEDs > Researchers Propose New Technology without Rare Earth Metals for LED Lighting
Technology | Aug 21, 2015

Researchers Propose New Technology without Rare Earth Metals for LED Lighting

At the 250th meeting of the American Chemical Society a novel approach to generate white light without using rare earth metals was presented. The reaserachers claim that this approach will lead to cheaper warm white LEDs than the currently used technologies. A press conference on this topic was held on Wednesday, Aug. 19, at 9 a.m. Eastern time in the Boston Convention & Exhibition Center.

Highly efficient, light-emitting diodes (LEDs) could slash the world’s electricity consumption. They are already sold in stores, but more widespread adoption of the technology has been hindered by high costs due to limited availability of raw materials and difficulties in achieving acceptable light quality. But researchers will report today that they have overcome these obstacles and have developed a less expensive, more sustainable white LED.

The scientists will discuss their research at the 250th National Meeting & Exposition of the American Chemical Society (ACS). ACS is the world’s largest scientific society. The national meeting, which takes place here through Thursday, features more than 9,000 presentations on a wide range of science topics.

“If more people in the U.S. used LEDs in their homes and businesses, the country’s electricity consumption could be cut in half,” says Zhichao Hu, Ph.D., a member of the Rutgers University team that performed the research under the direction of Jing Li, Ph.D. At that time, he was a graduate student. He is now a postdoc at Rutgers and is studying the recovery of rare-earth elements there. Zhichao adds that studies show substituting one LED light for a common incandescent light bulb in every American household could save the nation $700 million annually in energy costs.

To achieve the common, soft white light that consumers expect, current LED technologies typically use a single semiconductor chip to produce light, usually blue, and then rely on a yellow-emitting “phosphor” coating to shift the color to white. That’s because LEDs do not emit a white light. The phosphor is made from materials, such as cerium-doped yttrium aluminum garnet, that are composed of rare-earth elements. These elements are expensive and in limited supply, since they are primarily available only from mining operations outside the U.S. Additionally, the light output of these phosphors tends to be harsh, “cold” colors.

Li’s team is developing hybrid phosphor-based technologies that are much more sustainable, efficient and low-cost. They combine common, earth-abundant metals with organic luminescent molecules to produce phosphors that emit a controllable white light from LEDs. By varying the metal and organic components, the researchers can systematically tune the color of the phosphors to regions of the visible light spectrum that are most acceptable to the human eye, Hu and Li note. The team is continuing to experiment and develop other rare-earth-free LED phosphors based on different metals and organic compounds.

Many material combinations are possible, so they use a computational approach to initially sort through the possibilities and to predict what color of light the various metals and organics combinations will emit. They then test the best combinations experimentally.

Their approach allows a systematic fine tuning of band gaps and optical emissions that cover the entire visible range, including yellow and white colors. As a result, their LEDs can be fine-tuned to create a warmer white light, similar to cheaper but inefficient incandescent lights. Their approach shows significant promise for use in general lighting applications.

“One of challenges we had to overcome was to figure out the right conditions to synthesize the compound,” Hu notes. “Like cooking, the synthesis requires a ‘recipe.’ It’s often not the case that one can simply mix the starting materials together and get the desired product. We optimized the reaction conditions — temperature and the addition of a solvent — and developed an easy procedure to make the compound with high yield.”

Experiments with some materials have shown that the team’s technology can cut LED costs by as much as 90 percent from current methods that rely on rare-earth elements. They have several granted and pending U.S. patents and are exploring manufacturing possibilities.

Funding for this research was provided by the National Science Foundation and Rutgers University. Hu is currently funded by the Department of Energy’s Critical Materials Institute.

The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 158,000 members, ACS is the world’s largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

FEATURED

When Very High Light Output and Efficiency are Required for Demanding Applications, New LUXEON 7070 Checks All the Boxes

When Very High Light Output and Efficiency are Required for Demanding Applications, New LUXEON 7070 Checks All the Boxes More lumens, higher efficacy, and lower system costs are the driving forces behind new designs for a broad range of indoor and outdoor high light output applications. Lumileds new LUXEON 7070, introduced today, is designed to outperform similar lead-frame and ceramic high-power solutions with ... Read more »

FEATURED

NEW Extreme High Power LEDs Deliver Best Optical Performance

NEW Extreme High Power LEDs Deliver Best Optical Performance New XLamp® XHP70.3 LEDs deliver the best lumen density, reliability and optical control available in a 7x7 mm footprint.   Read more »

FEATURED

Edison Opto UVA + W & UVC Series Customize Design Solution

Edison Opto UVA + W & UVC Series Customize Design Solution Edison Opto offers customized UVA + White and UVC solutions for continuous disinfection to reduce bacteria and airborne viruses. In the wake of the global outbreak of COVID-19, the people’s need for anti-epidemic, sterilization, and anti-virus products has escalated, ranging from portable ... Read more »

EDITORIAL

deLIGHTed Talks: Good Light – Good Life in Wintertime, November 3, 2021

deLIGHTed Talks: Good Light – Good Life in Wintertime,  November 3, 2021 The Good Light Group, together with the Society for Light Treatment and Biological Rhythms (SLTBR), the Daylight Academy (DLA), the International Association of Lighting Designers (IALD), and Luger Research (LR), are organizing and presenting the “Good Light – Good Life” lectures. The webinar ... Read more »

page_peel