How is the white LED realized?

There are the following three major ways to realize the white LED:

1. White LED Utilizing Red, Green and Blue (RGB) LEDs: This method is also called RGB emission, taking the initial letter of each color. It features high reproducibility of color by combining the three primary colors of light.
2. White LED Utilizing a Blue LED and a Fluorescent Material: This is the major technology among the currently used white LEDs. White color is generally produced by a combination of a blue LED and a yellow fluorescent material. The light of the blue LED is partly absorbed, excited and converted into a yellow light by the yellow fluorescent material, thus providing the white color by blue and yellow lights. This method is easy to use because the white color is provided with a single package, but it has a drawback of low color rendering properties since the white color is provided by the blue and yellow colors.
3. LED Utilizing an Ultraviolet LED and a Fluorescent Material: White color is produced by an ultraviolet LED and RGB fluorescent materials. This white LED is capable of producing white color with a single package and has high color rendering properties.