Light in the 21st Century--A Brief Analysis of the Development of White Light LED Products

Technical Overview of White Light LED
Since the emergence of light-emitting diodes (LEDs), people have been striving to achieve solid light sources. With the continuous advancement of LED manufacturing technology and the development and application of new materials (nitride crystals and phosphors), the performance of LED semiconductor solid light sources that emit white light has been continuously improved and entered the practical stage. The emergence of white light LEDs has enabled the application field of high-brightness LEDs to enter the high-efficiency lighting source market. It has been pointed out that high-brightness LEDs will be one of the greatest inventions of mankind after Edison invented the incandescent light bulb. The so-called white light is a mixture of multiple colors. In the form of white light visible to the human eye, at least two types of light must be mixed, such as two-wavelength light (blue light + yellow light) or three-wavelength light (blue light + green light + red light). Currently, the only commercialized product is a two-wavelength blue light single chip plus YAG yellow phosphor. In the future, three-wavelength light is more promising, with inorganic ultraviolet light chips plus RGB three-color phosphors. In addition, organic single-layer three-wavelength white light LEDs also have the advantages of low cost and easy production. It is expected that three-wavelength white light LEDs will have the opportunity to be commercialized this year. In the future, they will be used in markets such as replacing fluorescent lamps, compact energy-saving fluorescent bulbs and LCD backlight sources, which will greatly help the market growth of white light LEDs.

In terms of technology, white LEDs are currently divided into two main light-emitting methods: the main commercialization method is that Nichia uses a layer of YAG fluorescent material on InGaN blue light grains with a wavelength of 460nm, and uses blue light LEDs to illuminate this fluorescent material to produce 555nm wavelength yellow light that complements the blue light. Then, the lens principle is used to mix the complementary yellow light and blue light to obtain the white light required by the naked eye. The development of white LEDs is based on blue light technology. Currently, Nichia is still the leader in blue light LED technology and has many patents. The second method is that Sumitomo Electric Industries of Japan has also developed white light LEDs using ZnSe as the material, but the luminous efficiency is poor. However, due to the current hot sales of white light LEDs in the market, there is still a phenomenon of supply exceeding demand.

Industry Overview

Among LED manufacturers, Nichia was the first to use the above-mentioned technology to develop high-brightness LEDs of different wavelengths, as well as blue-violet semiconductor lasers (Laser Diode; LD). It is a heavyweight manufacturer in the industry that holds the patent rights for blue LEDs. After Nichia obtained many basic patents such as blue LED production and electrode structure, it insisted on not providing authorization to others and only adopted a self-production strategy in an attempt to monopolize the market, making blue LEDs expensive. However, other manufacturers that already have production capabilities do not agree with this. Some Japanese LED manufacturers believe that Nichia's strategy will gradually make Japan lose the upper hand in the competition for blue and white LEDs to LED manufacturers in Europe, the United States and other countries, which will cause serious damage to the entire Japanese LED industry. Therefore, many manufacturers have tried every means to develop and produce blue LEDs. At present, in addition to Nichia Chemical and Sumitomo Electric, Toyota Gosei, Romu, Toshiba and Sharp, American Cree, the world's three largest lighting manufacturers General Electric, Philips, Osram, as well as HP, Siemens, Research, EMCORE, etc. have invested in the research and development and production of this product, which has played a positive role in promoting the industrialization and marketization of white light LED products.

Characteristics of white light LED

White light LED is the most promising new LED product, and its development potential in the lighting market is worth looking forward to. Compared with incandescent tungsten filament bulbs and fluorescent lamps, LED has the advantages of small size (multiple pieces, multiple combinations), low heat generation (no heat radiation), low power consumption (low voltage, low current start), long life (more than 10,000 hours), fast response speed (can be operated at high frequency), environmental protection (shock-resistant, impact-resistant and not easy to break, waste can be recycled, no pollution), flat packaging and easy to develop into thin and short products. It does not have the disadvantages of incandescent bulbs such as high power consumption and fragility, and the problem of mercury pollution in fluorescent lamp waste. It is expected by the industry to become a potential product to replace traditional lighting fixtures in the next 10 years.