Luminescent properties of rare earth luminescent materials
Rare earth luminescence is caused by the jump of rare earth 4f electrons between different energy levels. Because of different excitation modes, luminescence can be divided into photoluminescence, cathodoluminescence, electroluminescence, radioactive luminescence, X-ray luminescence, triboluminescence, chemistry. Luminescence and bioluminescence. Rare earth luminescence has strong absorption capacity, high conversion efficiency, and can emit spectrum from ultraviolet ray to infrared light, especially in the visible light region. Rare earth luminescent materials have been widely used in display imaging, new light sources, X-ray illuminating screens and other aspects.
The rare earth luminescent material has a narrow spectral band, high color purity, bright color, strong light absorption capability, high conversion efficiency, wide emission wavelength distribution region, and fluorescence lifetime from nanoseconds to milliseconds, reaching 6 orders of magnitude; stable physical and chemical properties. High temperature resistant, able to withstand high power electron beam, high energy radiation and strong ultraviolet light. It is these excellent properties that make rare earth compounds the main research object for the exploration of high-tech materials. And with the deepening of modern scientific research.
Research on rare earth luminescent materials has begun to trend toward nanocrystallization. Nanocrystallization of rare earth luminescent materials will undoubtedly give them some new properties of nanoparticles based on the above original characteristics, such as quantum size effect, small size effect, surface effect and macroscopic. Tunneling and so on. It can be seen that nanocrystallization of rare earth luminescent materials will inject new vitality into scientific research in this area, which will be more conducive to the discovery of new luminescent materials and new luminescent properties.
Application Status of Rare Earth Luminescent Materials in LED Industry
It is precisely because rare earth luminescent materials have the advantage that general luminescent materials cannot be replaced, so it is widely used in electric light source lighting, television color developing materials, agricultural conversion materials, X-ray fluorescent powders, luminescent coatings and luminescent inks. Among them, electric light source illumination is the most important aspect of its application, and the production of phosphor powder for lamps is the first among all phosphors.
At present, the application ratio of global incandescent lamps, halogen powder fluorescent lamps and energy-saving lamps is currently about 4:3:1, and China is about 8:9:1. Energy-saving lamps are the most mature environmentally-friendly and energy-saving lighting products in the current application technology. They are the main application and promotion targets for implementing energy-saving emission reduction, speeding up the elimination of incandescent lamps and achieving energy-saving lighting in the current lighting field. At present, China is the world's largest producer of lighting products. In 2009, the output of incandescent lamps in China was 2.73 billion, and the output of fluorescent lamps was 3.5 billion. Among them, the output of energy-saving lamps was about 3 billion, accounting for more than 85% of the total output of fluorescent lamps. Therefore, in the face of huge stock market and incremental market, the elimination of incandescent lamps, the promotion of energy-saving lamps and the accelerated replacement of halogen powder lamps will drive the rapid development of China's energy-saving lamp production industry.
The current output of rare earth luminescent materials is reduced, but the technology has been greatly improved. In 2009, the sales volume of rare earth luminescent materials for energy-saving fluorescent lamps in China was 6,160 tons, accounting for 74.13% of the total sales volume of rare earth luminescent materials industry. From 2010 to 2013, China's luminescence The application of rare earth in materials dropped from 5,000 tons to 2,600 tons, accounting for a total consumption ratio of rare earths from 5.78% to 3.1%. However, the technology of rare earth luminescent materials has been improved. In 2013, the market share of domestically produced LED powder exceeded that of imported powder, but there is still a certain gap with foreign technology. With the implementation of the phase-out of incandescent lamps, LEDs will achieve explosive growth with a penetration rate of 20%. In 2013, the output of LED lamps exceeded 810 million.
Application prospect of rare earth luminescent materials in LED industry
The rare earth long afterglow luminescent material is a new type of environmentally-friendly and energy-saving material that can store part of the energy after absorbing the energy of sunlight and light, and then slowly release the stored energy in the form of visible light, after the light source is removed. It can emit visible light for a long time, and also has excellent properties such as high temperature resistance, friction resistance, high strength, scratch resistance, flame retardancy and high chemical stability. It is an ideal energy-saving and environmentally friendly long-life optical material in construction, transportation and national defense. Other fields have important value.
In the aspect of light conversion agricultural film, the luminescent material is used as a light conversion agent for sunlight, and is added into an agricultural plastic film to form an agricultural film, which can improve the light quality of photosynthesis and improve the utilization rate of light energy of crops, thereby promoting the precocity of crops. And increase production.
In the field of lighting, solid white LEDs, which enjoy the reputation of the fourth generation of lighting sources, are attracting more and more researchers' attention with their outstanding advantages of energy saving, environmental protection and long life. LED will become a new generation of environmental protection and energy saving light source in the 21st century. It is precisely because of its irreplaceable advantages of other lighting sources, countries around the world including China, the United States, Japan and Europe have increased their research in this field, and they are competing to seize the intellectual property rights in this field.
In view of the excellent performance of energy-saving lamps in terms of light efficiency and longevity, in the context of global response to climate change and energy shortage, in recent years, many countries and regions around the world have introduced plans to ban the use of incandescent lamps and promote the use of energy-saving lamps. From a global perspective, the development trend of energy-saving lamps replacing incandescent lamps is irreversible.
Compared with halogen powder fluorescent lamps, energy-saving lamps (rare earth fluorescent lamps) using rare earth luminescent materials have higher luminous efficiency, better color rendering and longer service life, and energy-saving lamps can save 30% on the basis of halogen powder fluorescent lamps. -50%, the color rendering index is increased by 15%-40%, and the service life is increased by more than 3 times.
It is understood that the existing LED lighting source uses DC power as the driving, and must be converted by AC and DC power during operation. It has large energy consumption, poor heat dissipation and high cost. Therefore, it is beneficial to develop new LED lighting products that can be directly driven by AC. The people and the major demand for the development of the LED lighting industry. In addition, at present, this series of products have passed the relevant certification in China, as well as the American Underwriters Laboratories (UL), the United States Federal Communications Commission (FCC), the European Union (CE) and the European Union Environmental Protection (RoHS) certification, and sold to the United States, Canada, Mexico, Spain, Brazil and other countries have achieved significant economic benefits.
In June 2013, the Chinese Academy of Sciences (Caiyuan) Spring Applied Chemistry Research Institute and Chengdu Sichuan Xinli Light Source Co., Ltd. jointly developed the "light-emitting afterglow life controllable rare earth LED luminescent materials research and development and its application in semiconductor lighting" results, recently Approved by the results of the organization organized by the Chinese Academy of Sciences. The expert group believes that the original rare earth luminescent material effectively solves the stroboscopic problem of AC LED lighting equipment that has not been broken internationally, and has realized the leap from basic research to industrialization, reaching the international leading level and making China the world. The only country that has mastered the production of low frequency flash AC LED products through rare earth phosphors.
The demand for rare earth phosphors for energy-saving lamps is increasing. There are two main reasons: First, the development of low-carbon economy has become a global hotspot in recent years. The use of energy-saving lamps can greatly reduce carbon emissions. Increased the productivity of LED energy-saving lamps; Second, because China has strengthened the control of the export of rare earth raw materials in recent years, the production costs of foreign manufacturers have increased, and gradually withdrew from the low-profit market for rare earth luminescent materials for energy-saving lamps. In the next few years, with the implementation of the incandescent lamp elimination policy and the increasing demand for the downstream flat panel display market, the development prospects of rare earth luminescent materials in the LED lighting application market are good, and the growth potential is expanding.
to sum up:
With the rise of energy-saving lighting, rare earth luminescent materials in the LED industry, new technologies and new products emerge one after another, the industrial application of rare earth luminescent materials has exploded, and rare earth luminescent materials have become an indispensable basic material in the production of energy-saving lighting and special light sources. With the continuous expansion of the application field, the rare earth luminescent materials industry will have great potential in the LED lighting industry in the future.
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