Light-emitting diode superior for illumination in terms of color rendering, whereas one cannot appreciate the color of red or green objects illuminated only by the yellow (and remaining blue) wavelengths from the YAG phosphor. The first white LEDs were expensive and inefficient. However, the light output of LEDs has increased exponentially, with a doubling occurring approximately every 36 months since the 1960s (similar to Moore's law). The latest research and development has been propagated by Japanese manufacturers such as Panasonic, Nichia, etc. and later by Korean and Chinese factories and investment such as: Samsung, Solstice, Kingsun, and countless others. This trend is
Light-emitting diode epoxy, synthetic rubber or silicone. Touching bare LEDs using synthetic rubber or silicone can damage the delicate wire bonds from LED to package or the LED itself, so they may be protected by a plastic or glass cover, such as in the LED flash in smartphones. It is this YAG phosphor which causes white LEDs without diffusers (such as those used in LED lamps and bulbs) to look yellow when off. There are three main methods of mixing colors to produce white light from an LED: Because of metamerism, it is possible to have quite different spectra that appear white.