LED phosphor materials are indispensable China has initially broken foreign patent restrictions

White LED has remarkable advantages such as high luminous efficiency, long life, energy saving and environmental protection, and has broad application prospects in the fields of green lighting and information display. At present, the core materials of commercial white LEDs are blue LED chips and phosphors, which are indispensable. Although there are many alternative technical solutions, from the perspective of development trends, the use of phosphors combined with blue LED chips will always be the mainstream production method of white LEDs. Therefore, phosphors are very important for the LED lighting and liquid crystal display industries. Governments, research institutions and industry have attached great importance to this, and have invested a lot of manpower and material resources for research and development.

Initial breakthrough in foreign patent restrictions

At present, the rare earth yttrium-activated garnet-structured yttrium aluminum yttrium yellow phosphor with blue LED light has the best luminous efficiency. However, due to the serious shortage of red light in the red part, the white LED product has poor color rendering. It is impossible to use this single phosphor to prepare a white LED with low color temperature and high color rendering. When the blue chip yellow powder product is used as an illumination source, it is excessively cold in visual sense; when it is a liquid crystal backlight, the display color gamut is narrow, and the full color effect is not good. The display index of white LED devices made with blue chip yellow pink powder has been greatly improved (above 80), but to obtain a higher display index (above 90), green phosphors must also be added.

In the development of LED phosphors, sulfides, sulfur oxides, tungsten molybdates, citrates, arsenates, and barium silicates have all been developed and tried, but the phosphors of these systems exist. The disadvantages of poor stability, low excitation efficiency, and high cost have not been widely applied. At present, strontium aluminate powder will play an irreplaceable role due to its high light efficiency and excellent structural and chemical stability. The nitride and oxynitride phosphors become white light with their unique structure, excellent luminescence properties and stability. The focus of research and development and application of LED red and green phosphors.

Due to the late development and development of LED phosphors in China, the foreign countries have taken a favorable position in the patents of LED phosphors. For example, strontium aluminate phosphor with garnet structure is a relatively traditional phosphor material. Because of its ultra-short afterglow characteristics, it was widely used in flying spot scanners in the 1960s. Therefore, the phosphor itself does not have a patent. problem. In 1997, Nichia used GaN chips to match the phosphor to obtain white light and applied for a patent. Another example is the silicate system material commonly used in liquid crystal backlight white LEDs, which was widely used as a long afterglow material in the early days. However, in the patent layout of silicate phosphors for LEDs, foreign countries have taken the lead. After several years of development, domestic Rare Earth and Dalian Luming have initially broken foreign patent restrictions in terms of aluminate yellow powder and silicate green powder, and the product quality is basically equivalent to foreign standards. Nitride/nitrogen oxide phosphors have good market prospects as LED red and green phosphors due to their wide excitation and emission range, high luminous efficiency, and good chemical and thermal stability. In the patent of nitride/nitrogen oxide system, foreign companies such as Mitsubishi Chemical of Japan have taken advantage, and the research on the composition and preparation process of nitride/nitrogen oxide phosphor has been systematically studied by the research institute of rare earth and other units. Series of patents.

Focus on quality rather than price

Unlike the three-primary phosphors used in energy-saving lamps, LED phosphors are unique. First, LED phosphors account for only 1% to 2% of the cost of white LED devices. LED packaging manufacturers first focus on product quality, not price, so only the first-class products can survive in the LED phosphor market; second, LED chips and packages The technology is constantly improving, and at the same time, the performance of the phosphors is required to continue to progress and change. Only companies with deep R&D accumulation and strong continuous innovation can survive. Third, most of China's LED products are exported rather than domestically sold. In terms of patents, unpatented phosphors are difficult to enter the market. For the above reasons, although there are no fewer than 20 manufacturers in China that can produce LED phosphors, except for a few companies such as rare earths, the market for white LED phosphors is basically Japanese fundamental chemistry (market brand is Taiwan Hongdae). ) and the United States, the United States and the United States to occupy, the domestic white LED phosphor market share of less than 20%. In recent years, Japan's Mitsubishi Chemical has rapidly seized market share with the advantage of nitride red powder, and recently announced the establishment of LED phosphors in Xi'an.

Rare earth has been engaged in the research and development of phosphors for more than 40 years. It has been engaged in the research and development of LED phosphors for more than 10 years. It has been used in phosphoric acid systems such as aluminates, silicates, aluminosilicates and nitrides. In terms of LED devices, it has applied for more than 30 Chinese invention patents and more than 10 foreign invention patents. More than 10 Chinese invention patents and 5 foreign invention patents have been authorized. Through the implementation of the patent license, the export rights of many large packaging companies in China are guaranteed.

According to the experience of the industry, to increase the market share of domestic LED phosphors, it is necessary not only to work on the existing phosphor system, but also to further accelerate the development of new phosphors and obtain independent intellectual property rights, so that it is possible in the market. Get more voices to further protect the health and sustainable development of China's LED industry.

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