The History of LED: From Discovery to Revolution

Origin

In the 1960s, scientists developed LED based on the principle of semiconductor PN junction. The LED developed at that time was made of GaASP and its luminous color was red. After nearly 30 years of development, we are very familiar with LED, which can emit red, orange, yellow, green, blue and other colors. However, the white LED for lighting was developed only after 2000. Here we introduce the white LED for lighting.

Development

The first LED light source made of semiconductor P-N junction light emission principle was introduced in the early 1960s. The material used at that time was GaAsP, emitting red light（ λ P=650nm), when the driving current is 20mA, the luminous flux is only a few thousandths of lumen, and the corresponding optical efficiency is about 0.1 lumen/watt.

In the mid-1970s, the elements In and N were introduced to make LED produce green light（ λ P=555nm), yellow light（ λ P=590nm) and orange light（ λ P=610nm).

In the early 1980s, GaAlAs LED light source appeared, making the luminous efficiency of red LED reach 10 lumens/watt.

In the early 1990s, two new materials, GaAlInP emitting red and yellow light and GaInN emitting green and blue light, were successfully developed, which greatly improved the luminous efficiency of LED.

In 2000, the LED made of the former was in the red and orange areas（ λ P=615nm), and the LED made of the latter is in the green area（ λ P=530nm).

Lighting Chronicle

- 1879 Edison invented the electric lamp;

- 1938 Fluorescent lamp came out;

- 1959 Halogen lamp came out;

- 1961 High pressure sodium lamp came out;

- 1962 Metal halide lamp;

- 1969, the first LED lamp (red);

- 1976 green LED lamp;

- 1993 blue LED lamp;

- 1999 white LED lamp;

- 2000 LED shall be used for indoor lighting.

- The development of LED is the second revolution following the 120-year history of incandescent lighting.

- At the beginning of the 21st century, LED, which is developed through the wonderful encounter between nature, human beings, and science, will become an innovation in the light world and an indispensable green technological light revolution for mankind.

- LED will be a great light revolution since Edison invented the light bulb.

LED lamps are mainly high-power white LED single lamps. The top three LED lamp manufacturers in the world have a three-year warranty. Large particles are more than or equal to 100 lumens per watt, and small particles are more than or equal to 110 lumens per watt. Large particles with light attenuation are less than 3% per year, and small particles with light attenuation are less than 3% per year.

LED swimming pool lights, LED underwater lights, LED fountain lights, and LED outdoor landscape lights can be mass-produced. For example, a 10-watt LED fluorescent lamp can replace a 40-watt ordinary fluorescent lamp or energy-saving lamp.