LED (Light Emitting Diode), a solid-state semiconductor device that converts electrical energy into visible light, converts electricity directly into light. The heart of the LED is a semiconductor wafer with one end attached to a holder, one end being the negative pole and the other end connected to the positive pole of the power supply, so that the entire wafer is encapsulated by epoxy.
The semiconductor wafer consists of two parts, one part is a P-type semiconductor, in which the hole dominates, and the other end is an N-type semiconductor, which is mainly electrons here. But when the two semiconductors are connected, they form a P-N junction. When a current is applied to the wafer through the wire, the electrons are pushed toward the P region. In the P region, the electrons recombine with the holes, and then the energy is emitted in the form of photons. This is the principle of LED light emission. The wavelength of light, which is the color of light, is determined by the material that forms the P-N junction.