"Light-emitting diode (LED) is a semiconductor device based on the effect of electroluminescence. Due to the limitation in efficacy and the lack of white light, LED was not suitable for general lighting applications in the past. With the advancement of semiconductor materials and packaging technologies, the illumination performance of LED has been greatly improved. Ten years ago high power (one watt) white LEDs were introduced with efficiencies high enough to trigger serious discussions on using LEDs for solid-state lighting (SSL) applications."-- Provided by publisher.