In the 60s of the last century, scientific and technological workers used the principle of semiconductor PN junction luminescence to develop LED light-emitting diodes. The LED developed at that time used GaASP, its luminous color is red. After nearly 30 years of development, the LED that everyone is very familiar with has been able to emit red, orange, yellow, green, blue and other color lights. However, the white LED for lighting was only developed after 2000, and the reader is introduced to the white LED for lighting. The earliest LED light source made of semiconductor P-N junction luminescence principle came out in the early 60s of the 20th century.
The material used at that time was GaAsP, which glowed red (λp = 650nm), and at a drive current of 20 mA, the luminous flux was only a few thousandths of a lumens, and the corresponding luminous efficiency was about 0.1 lumens per watt. In the mid-70s, the elements In and N were introduced to make LEDs produce green light (λp=555nm), yellow light (λp=590nm) and orange light (λp=610nm), and the light efficiency was also increased to 1 lumen/watt. By the early 80s, the GaAlAs LED light source appeared, making the red LED light efficiency reach 10 lumens per watt. In the early 90s, two new materials, GaAlInP, which emits red and yellow light, and GaInN, which emits green and blue light, were successfully developed, which greatly improved the light efficiency of LED. In 2000, the LED made of the former achieved a light efficiency of 100 lumens/watt in the red and orange regions (λp=615nm), while the LED made of the latter could reach 50 lumens/watt in the green area (λp=530nm).
Post time: Nov-11-2022