①In 1962, the joint laboratory of GE, Monsanto, and IBM developed a red-emitting gallium arsenide phosphide (GaAsP) semiconductor compound. Since then, visible light-emitting diodes have entered the commercial development process. ②In 1965, the world's first commercial light-emitting diode was born. It is an LED made of germanium material that emits infrared light. The unit price at that time was about 45 US dollars. Shortly thereafter, Monsanto and Hewlett-Packard introduced commercial red LEDs made of GaAsP materials. The efficiency of this LED is about 0.1 lumens per watt, which is more than 100 times lower than the 15 lumens per watt of typical 60 to 100 watt incandescent lamps. ③In 1968, a breakthrough was made in the research and development of LEDs. The efficiency of GaAsP devices reached 1 lumen/watt using nitrogen doping process, and it was able to emit red, orange and yellow light. ④In 1971, the industry introduced a GaP green chip LED with the same efficiency. ⑤ By the 1970s, the price of LEDs plummeted due to the massive application of LED devices in home and office equipment. In fact, the main market of LED in that era was the application field of digital and text display technology. ⑥ A major technological breakthrough in the early 1980s was the development of AlGaAsLED, which emits red light with a luminous efficiency of 10 lumens per watt. This technological advance enables LEDs to be used in outdoor information distribution as well as in automotive high-mounted stop light (CHMSL) devices. ⑦In 1990, the industry developed AlInGaP technology that can provide the best red device performance, which is 10 times higher than the standard GaAsP device performance at that time. ⑧ Today, the most efficient LEDs are made of transparent substrate AlInGaP material. Between 1991 and 2001, further developments in material technology, chip size and form factor increased the luminous flux of commercial LEDs by a factor of nearly 30. ⑨ In 1994, Japanese scientist Nakamura Shuji developed the first blue light-emitting diode on a GaN substrate, which triggered an upsurge in the research and development of GaN-based LEDs. In 1996, the white LED was successfully developed by Nichia Corporation of Japan (Nichia). ⑩In the late 1990s, LEDs that produced white light by exciting YAG phosphors with blue light were developed, but the color was uneven, the service life was short, and the price was high. With the continuous advancement of technology, the development of white LEDs has been quite rapid in recent years. The luminous efficiency of white LEDs has reached 38lm/W, and the laboratory research results can reach 70lm/W, which greatly exceeds incandescent lamps and approaches fluorescent lamps.