1. LED structure and working principium.
50 years ago, people had understood a basic knowledge of the semiconductor material can generate light, the first commercial diode produced in 1960. LED stand for light-emitting diode, its basic structure is an electroluminescent semiconductor material, placed in a wire rack, then sealed by epoxy resin for protection the chip in the core, so LED performance better seismic.
The core parts of the light-emitting diode is the chip composed by p-type semiconductor and n-type semiconductor, there is a transition layer between the P and N semiconductor which known as the PN junction. In some PN junction of semiconductor materials, when the injected minority carrier and majority carrier recombination, it will release the excess energy in the form of light, which converts electrical energy directly into light. When PN junction in reverse voltage, the minority-carrier injection is difficult and result no light. Such diodes produced by the principle of injection electroluminescent called light-emitting diodes, known as LED. When it is working in condition of the forward current (ie, ends with a positive voltage), current flows from the anode to cathode, the semiconductor crystal issues different colors from the ultraviolet to infrared light, light intensity depend on the current.
2. LED benefits.
1) Low Voltage: LED working on low-voltage power supply, according to different products, the voltage is between 6-24V. So it's more secure than the use of high voltage products, especially for public places.
2) Energy efficiency: energy consumption is 80% less than the incandescent lamps.
3) Wide Applicability: each unit LED is square with side of 3-5mm, it's small and can be made into various shapes of the devices, and suitable for the volatile environment.
4) Good Stability: LED light decay for 100,000 hours is 50%.
5) Quick Response time: incandescent light with milliseconds response time, but LED lamp with nanosecond response time.
6) Protect Environment: non-hazardous metallic such as mercury.
7) Colorful: It can change color by changing the current, LED can easily adjust the material structure and band-gap by chemical modification methods, finally achieve multi-color light-emitting, such as orange, Blue, red, yellow and green. It's red color when in small current, as the current increases, you can turn into orange, yellow, and finally the green.
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