Typical white light-emitting diodes [LED] are extremely bright and expensive to manufacture. Their applications are also limited because of the directional nature of the light they produce. Japanese researchers have developed a new white LED, using a different phosphor compound, that eliminates these issues.
The new yellow phosphor, “CL_MS phosphor,” was co-developed by Koito Manufacturing Co Ltd, and research groups led by Professor Hideo Hosono of Tokyo Institute of Technology and Professor Hiroshi Sawa of Nagoya University.
Koito Manufacturing’s “new layered crystal structure” LED combines a purple LED chip, a layer of blue phosphor, and the new yellow phosphor, into a package 10mm in diameter. The blue phosphor was applied at about 95% less density than in typical white LEDs, with the new yellow phosphor to convert the purple light at about 94% efficiency.
The new crystal formulation has a number of advantages. Light emitted from the new LED is not as directional, being diffused across the whole surface of the 10mm semi-spherical package. The LED can be manufactured in different shapes with no loss in brightness. If the LED is installed in a fixture, Koito Manufacturing says it can light up the entire room.
The oxide-based self-fluxing crystal material only requires about 800°C process temperature, unlike typical white LED manufacturing techniques, which require about 2,000°C, 10 atmosphere pressure, and an oxygen-free environment. Without these constraints, the new yellow-phosphor LED becomes much less expensive to manufacture.
