General knowledge about LED

LED lighting, as a new lighting solution, has attracted more and more attentions from the people inside and outside the lighting industry. However, there are still a lot of people who do not have general knowledge about LED, So LED business face a lot of difficulty in terms of marketing for the time being.
As the increasing requirments of LED lighting from the whole world, it is indeed necessary to publish the LED information for the people.
Here are some basic info about LED, hope it will be helpful for your understanding.
What is LED?
LED stands for Light Emitting Diode, a kind of semiconductor which is used to give and receive the electronic signal into infrared rays or light, using the characteristics of compound semiconductor. This is used for household appliances, remote controller, electric bulletin board, various kinds of automation appliances.
What Causes the LED to Emit Light and What Determines the Color of the Light?
When sufficient voltage is applied to the chip across the leads of the LED, electrons can move easily in only one direction across the junction between the p and n regions. In the p region there are many more positive than negative charges. In the n region the electrons are more numerous than the positive electric charges. When a voltage is applied and the current starts to flow, electrons in the n region have sufficient energy to move across the junction into the p region. Once in the p region the electrons are immediately attracted to the positive charges due to the mutual Coulomb forces of attraction between opposite electric charges. When an electron moves sufficiently close to a positive charge in the p region, the two charges "re-combine".Each time an electron recombines with a positive charge, electric potential energy is converted into electromagnetic energy. For each recombination of a negative and a positive charge, a quantum of electromagnetic energy is emitted in the form of a photon of light with a frequency characteristic of the semi-conductor material (usually a combination of the chemical elements gallium, arsenic and phosphorus). Only photons in a very narrow frequency range can be emitted by any material. LED''s that emit different colors are made of different semi-conductor materials, and require different energies to light them
How Much Energy Does an LED Emit?
The electric energy is proportional to the voltage needed to cause electrons to flow across the p-n junction. The different colored LED''s emit predominantly light of a single color. The energy (E) of the light emitted by an LED is related to the electric charge (q) of an electron and the voltage (V) required to light the LED by the expression: E = qV Joules. This expression simply says that the voltage is proportional to the electric energy, and is a general statement which applies to any circuit, as well as to LED''s. The constant q is the electric charge of a single electron, -1.6 x 10-19 Coulomb.