The origin of
In the 1960s, scientists developed LED light-emitting diodes 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, has been able to emit red, orange, yellow, green, blue and other colors. However, the use of white LED lighting only developed after 2000. Here we introduce the use of white LED lighting.
The development of
The earliest LED light source made of semiconductor p-n junction luminescence principle appeared in the early 1960s. The material used was GaAsP, or red light (lambda p=650nm), with a luminous flux of only a few thousandths of a lumen at a driving current of 20 milliamperes.
In the mid-1970s, the introduction of the elements In and N, LED to the production of green light (lambda =555nm), yellow light (lambda =590nm) and orange light (lambda =610nm), the luminous efficiency also increased to 1 lumen/watt.
By the early 1980s, GaAlAs LED light was introduced, which made red leds up to 10 lumens per watt.
In the early 1990s, LED optical efficiency was greatly improved with the successful development of two new materials, GaAlInP for red light and GaAlInP for yellow light and GaInN for green and blue light.
In 2000, the former was 100 lumens per watt for the red or orange zone, while the latter was 50 lumens per watt for the green zone.