White light LED using phosphor to realize there are three main methods, but they are not yet fully mature, thus seriously affecting the field of white-light LED lighting applications. Specifically, the first method is coated on a blue LED chip can be yellow phosphor excited by blue chip issued blue and yellow light complement each other to form white light from phosphors. The technology was Japan Nichia company monopoly, and a principle drawback of this scheme is the fluorescence emission spectra of the Ce3+ ions in the body have no continuous spectrum characteristics of poor color rendering, it is difficult to meet the requirements of low color temperature lighting, and high luminous efficiency are not enough, need to be improved by the development of new phosphor.
Second method is a blue LED chip coated with green and Red Phosphors, issued by chip Blu-ray issued the green light and red light and phosphor compound to get white color better. However, this method uses effective phosphor conversion efficiency is low, especially the Red phosphor efficiency greatly improved.
Third species achieved method is in violet or purple outside light glow diode chip Shang coated enough three color or variety color of fluorescent powder, using the chip launches of longwave purple outside light (370nm-380nm) or violet (380nm-410nm) to inspired phosphor and achieved white light launches, the method explicit color sex better, but also exists and second species method similar of problem, and currently conversion efficiency high of red and green phosphor more for sulfide system, this class phosphor glow stability poor, and light failure larger, Therefore the development of efficient, low light white LED using phosphor has become an urgent task.