Īppearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared (IR) light. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device. The color of the light (corresponding to the energy of the photons) is determined by the energy required for electrons to cross the band gap of the semiconductor.
Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. A bulb-shaped modern retrofit LED lamp with aluminum heat sink, a light diffusing dome and E27 screw base, using a built-in power supply working on mains voltageĪ light-emitting diode ( LED) is a semiconductor light source that emits light when current flows through it.
