60s of last century, science and technology workers using the principle of semiconductor PN junction luminescence, developed into a LED light-emitting diode. LED was developed, the material used is GaASP, the light color is red. After nearly 30 years of development, we are very familiar with the LED, has been issued red, orange, yellow, green, blue and other colors. However, white light LED lighting needs only developed after 2000, here to introduce readers to the white LED lighting.
The earliest application of semiconductor P-N junction LED light source made of light came out in the early 1960s. The material used at that time was GaAsP, red (λp = 650 nm), with a luminous flux of only a few thousandths of a lumen at a drive current of 20 mA, with a corresponding luminous efficiency of about 0.1 lm / W.
In the mid-1970s, the elements In and N were introduced to produce green light (λp = 555 nm), yellow light (λp = 590 nm) and orange light (λp = 610 nm).
By the early 1980s, there was a GaAlAs LED light source that enabled the red LED's luminous efficacy to reach 10 lumens / watt.
The early 90s, the red, yellow GaAlInP and hair green, blue GaInN two new successful development of the material, the LED light efficiency has been greatly improved. In 2000, the former LED produced 100 lumens / watt of light in the red and orange regions (λp = 615 nm) while the latter produced 50 lumens / watt of light in the green region (λp = 530 nm) watt.