White LED drive domestic development promoting technological progress phosphor fluorescent powder

White LED and its combination light has many merits such as solid, small volume, long service life, not easy to damage, earthquake, start fast response time, low power consumption, pollution-free, known as the fourth generation light source, also known as the green light in twenty-first Century. The preparation of white LED with phosphor is the mainstream of the current development, so the progress of phosphor technology has a very important role in the development of white LED. White LED July 29, 1996 Nichia in Japan's first declaration of the patent of invention is in a blue LED chip coated YAG yellow phosphor, and blue fluorescent powder through the chip issued a yellow light complementary white. In fact, YAG phosphor is a fluorescent powder in 1970s it has been widely investigated, the main field of application is the flying spot scanner, mainly using the characteristics of Ce3+ with ultrashort afterglow luminescence. It is worth mentioning that the Beijing Nonferrous Metal Research Institute of Rare Earth Research Laboratory (grirem new materials Limited by Share Ltd predecessor) in early 80s developed a series of YAG phosphors for flying spot scanner, won the Ministry of Metallurgical Science and technology progress award. In 1999, the company was improved in grirem basis for YAG phosphor flying spot scanner on the preparation of a series of different emission peak wavelength (520 nm -560 nm) yellow phosphor for white LED, and successfully applied to blue light excitation, which has been applied for national invention patent a. The work has been funded by the national "863 Plan" to provide a fluorescent material for white light source. Has now formed by YAG fluorescent powder product series white LED small batch, the performance reaches or exceeds the level of foreign products, the supply of more than and 10 white LED devices Chinese factory in mainland China and Taiwan, have good social and economic benefits. In the white LED violet and ultraviolet excitation, the PHILPS company in the United States in May 27, 1997 to declare the "UV light emitting device LED+ fluorescent powder" of the invention patent, but the composition of patent does not involve the specific fluorescent powder. Grirem has begun violet and ultraviolet excitation for white LED phosphor in 2000 and in June 2001 respectively in bilateral new material Fifth Conference on South Korea and Beijing in the Fourth International Symposium on research and application of rare earth, the report can be used in the composition of three rare earth trichromatic phosphor white and violet LED the excitation of UV light, these phosphors have been used in white light violet and ultraviolet excitation in LED. GE company has a number of patents relating to the composition of the LED three excited phosphor powder UV. One of the earlier one was declared in the United States in May 26, 2000, the date of disclosure of the patent is in July 3, 2001. Two they reported the same blue powder and grirem is reported, but there are reports of rare earth luminous efficiency research and pink green powder are higher than they reported. Later in their patent, red and grirem the pink composition is basically the same, only to make some small changes, and replaced the composition of their original patent in pink. But the red luminescence efficiency is still not high enough, can not meet the requirements of the white LED, need to be further improved. In order to avoid the patent problem, some people put forward the "blue LED+ green phosphor + red phosphor" white LED structure. Now this structure has been widely recognized, in March 2003, the United States held the "2003 global fluorescent material summit", there are a number of companies reported the structure and the use of phosphors. Rare earth has developed two types of green phosphors for blue LED, and applied for a national invention patent. At present, the efficiency of red phosphors is too low, so we must develop new red phosphors. Generally speaking, in the recent years, the development of LED phosphor is very rapid. The United States GE company's largest patent, domestic patent reports. The yellow phosphor excited by blue light can basically meet the requirements of white LED products. However, it is necessary to further improve the efficiency and reduce the particle size, it is best to prepare spherical phosphor. In the structure of "blue LED+ green phosphor + red phosphor", the efficiency of green fluorescent powder can basically meet the requirements, but the efficiency of red phosphor is greatly improved. In the structure of "UV or violet LED+ three color phosphor", the efficiency of the three kinds of phosphors needs to be improved. Recently, some progress has been made in the field of red phosphors, but the phosphors with high luminous efficiency are mainly sulfide systems, which have poor stability. Therefore, it is necessary to develop a high efficiency and stable fluorescent powder to meet the needs of the development of semiconductor lighting technology.