Scientists develop long life, no rare earth containing LED phosphor

American researchers claim to have succeeded in developing cheaper, more durable white LED. They will discuss the invention at the 250th annual American Chemical Society (ACS) National Conference and exposition. From Rutgers University and participated in the study team member Zhichao Hu said: "if the United States has more people to use LED at home or business, so the power consumption can be reduced by half. "At that time, he was a graduate student. Now, he is a postdoctoral research at Rutgers University, the field of rare earth elements.

The current LED technology usually uses a single semiconductor chip to generate blue light, and then rely on yellow phosphor coating to convert the color to white. The phosphor is made of yttrium aluminum garnet doped with cerium (consisting of rare earth elements). These rare earth elements are very expensive and have limited supply, mainly from mining operations outside the United states.

The team is developing a technology based on mixed phosphorus, which claims that the technology can make LED's life longer, more efficient and cost less. They combined with ordinary metal rich soil and organic light-emitting molecules to produce controllable LED white phosphor. By changing the metal and organic components, the researchers can systematically adjust the color of the phosphor to the most acceptable area of the human eye visible spectrum. They also continue to test and develop other rare earth based LED phosphors with different metals and organic compounds.

There are many materials may be combined, so they first calculate the possibility of various sorting, predict various metal and organic combination will be issued what the color of light, and then find the best combination test.

They allow the system to fine tune the band gap and the optical emission of the entire visible range, including yellow and white. As a result, they developed LED lights to fine tune out a warm white light, similar to the cheap and inefficient incandescent lamp. This is of great significance in general lighting applications.

"One of the challenges we have to overcome is to find the right conditions for the synthesis of compounds," Hu said. Just like cooking, this kind of synthesis needs a recipe". It is not simply that the raw materials are mixed together to get the desired product. We need to optimize the reaction conditions, temperature, and the addition of solvent - and then develop simple steps to obtain high yields of compounds. "

The results of experiments on some materials show that the team can reduce the cost of LED 90% by using the present method. They have applied for U.S. patents and are exploring the possibility of production.

The project is funded by the National Science Foundation and the Rutgers University offers. Hu has also been funded by the National Institute of energy materials.

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