U.S. researchers claim they have successfully developed a white LED that is cheaper and lasts longer. They will discuss the invention at the recent 250th American Chemical Society (ACS) National Conference & Expo.
Zhichao Hu, a team member who is involved in the study at Rutgers University, said: "If more people in the United States use LEDs at home or in business, the country's power consumption can be cut in half." At the time, he was A graduate student Now, he is a Rutgers University postdoctoral, mainly in the field of rare earth elements.
Current LED technology typically uses a single semiconductor chip to generate blue light and then reverts the color to white with a yellow luminescent phosphor coating. This phosphor is made of cerium doped yttrium aluminum garnet (composed of rare earth elements). These rare earth elements are very expensive and have a limited supply, mainly from mining operations outside the United States.
The research team is developing a hybrid phosphorus-based technology that claims the technology will make LEDs last longer, more efficient, and cost less. They combine with common soil-rich metals and organic luminescent molecules to produce controlled LED white phosphors. By changing the metal and organic components, researchers can systematically adjust the color of the visible spectrum of the most acceptable region of the human eye for phosphors. They also continue to experiment with other rare earth-free LED phosphors based on different metals and organic compounds.
Many materials are possible combinations, so they initially calculated the possibility of various sorts, predicted the color of light emitted by the various metal and organic combinations, and then tested to find the best combination.
Their method allows for fine-tuning of the system by covering the bandgap and light emission over the entire visible range including yellow and white. As a result, the LED lamps they developed were able to fine tune a warm white light, similar to the low cost and incandescent lamp. This is of great importance in general lighting applications.
(Left: yellow phosphor coated LED, off state; right: open state)
Hu pointed out: "One of the challenges we have to overcome is to find suitable conditions for the synthesis of compounds." Like cooking, this synthesis also requires 'recipes.' It often does not simply mix the raw materials together We need to optimize the reaction conditions - temperature, solvent addition - and then make simple steps to get high yields of compounds. "
The results of experiments on certain materials show that the team is able to reduce 90% of the LED's costs using the current method. They have applied for a U.S. patent and are exploring the possibilities of production.
Funding for this project was provided by the National Science Foundation and Rutgers University. Hu is also currently funded by the National Institute of Energy Materials Research Institute.
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