Light Emitting Diodes are also known as LEDs. It uses a fixed semiconductor chip as a light-emitting material, so it is a semiconductor. Compared with traditional lamps, light-emitting diodes are more environmentally friendly and energy-saving, and have high color rendering. Semiconductor light-emitting diodes are simple in structure, small in size, small in operating current, easy to use, and low in cost, so they are widely used in optoelectronic systems. Under forward bias, the semiconductor PN junction or its similar structure can emit visible light or near-infrared light. This device that directly converts electrical energy into light energy is called a light-emitting diode, or LED for short. Luminescence is the process by which energy stored in some way inside an object is converted into light radiation. Light emission from a luminescent object is generated when excited electrons in the material transition to the ground state. Semiconductors (mainly compound semiconductors composed of Group III and Group V elements in the periodic table) light-emitting diodes are electroluminescent devices excited by current. The phenomenon of electroluminescence was discovered in 1923 and did not attract people's attention at the time. With the development of modern technology, new requirements are put forward for light-emitting devices. It is hoped that the light-emitting tube is simple, reliable, long-life, low-cost and miniaturized. Therefore, the research on electroluminescence has been very active since the 1960s. The material used at that time was GaAsP, which emits red light (λp=wavelength 650nm). When the driving current is 20mA, the luminous flux is only a few thousandths of lumens, and the corresponding luminous efficacy is about 0.1 lumen/watt.