New Yellow Fluorescent Material for White LED Production Technology Established

The Japanese Kosuke Seisakusho Co., Ltd. cooperated with the research group of Professor Toshio Hideo of the Tokyo Institute of Technology and the research team of Prof. Zebo of Nagoya University to develop a new type of yellow fluorescent material called "Cl_MS phosphor", which was mainly used in white LEDs for illumination. Koji Yoshihiko, vice president of the company's board, director of the technology department, and director of the Intellectual Property Department of the System Commodity Planning Division, said that compared with the existing products, the white LED using the Cl_MS phosphor “can not only be suitable for indoor lighting Soft light can also reduce costs." The specific time for mass production was not announced, but Yokoyama said that "the mass production technology of fluorescent materials has been established and is being negotiated with LED manufacturers and lighting manufacturers."

The quantum efficiency is 94%

The Cl_MS phosphor is made by adding the activator Eu(2+)2+, which is responsible for luminescence, to the parent crystal of the chemical formula (Ca1-x,Srx)7(SiO3)6Cl2, “a layered new crystal structure” (small Institute of silk production institute chief long long long Fang). Its characteristic is that the purple light can be converted to yellow light with a quantum efficiency of 94%; less blue light is absorbed when excited; the light emission spectrum is wide, and therefore the color expression is high.

Minor Filtration has developed a hemispherical white LED with a diameter of 10mm using a combination of Cl_MS phosphor, blue phosphor and violet LED chip. The small silk production company introduced a large length of presentation, "coating thicker Cl_MS phosphor and blue phosphor particles at a low concentration." Compared with the conventional white LED structure having a thickness of about 2 mm to about 3 mm, the phosphor particles have a concentration of 1/10 to 1/20.

White LED has five characteristics

The white LED developed this time has five characteristics. First, the luminous flux is high and bright. Compared to the original product using the same purple LED chip and phosphor, the luminous flux is increased by 25%. Since the phosphor particles are coated at a low concentration, shading and scattering between the particles are suppressed. Second, the brightness in the frontal direction is low, reducing the unique glare of white LEDs. Compared with a white LED made of a combination of a blue LED chip and a yellow phosphor (YAG), the light emitting area is increased to 10 times and the luminance is reduced to 1/10 when the luminous flux is the same.

Third, since light of two kinds of fluorescent materials is used to obtain white light, there is no directivity, and although it is a hemispherical structure having a diameter of 10 mm, white light unevenness does not occur. Using the same structure as the developed product, a white LED was fabricated by combining a blue LED chip and a yellow fluorescent material. As a result, it was found that the straight line of the blue light propagates strongly and the peripheral portion is yellow. In addition, a white LED with a combination of a red LED chip, a red, blue, and green phosphor material was also prototyped. Since the blue and green light are absorbed by the red fluorescent material, the surrounding redness occurs.

Fourth, by using a hemispherical structure with a diameter of 10 mm, the irradiation range is greater than before. When applied to LED lighting, it illuminates the entire room brightly. Fifth, the degree of freedom of shape is high. Because there is no directivity, not only can it be made hemispherical but also can be made into a cone or other shape.

The cost is also very low

Komori Seisakusho uses a self-fluxing method that uses a partially crystalline raw material as a solvent (flux) to make a Cl_MS phosphor. The processing temperature is about 800°C. Since it belongs to an oxide fluorescent material, "it does not require processing such as high temperature (2000°C), high pressure (10 atmospheric pressure), environmental control (anaerobic state), etc., like a nitride fluorescent material such as YAG, etc., and costs are reduced."