Principle of LED
It's a kind of semiconductor diode, can turn electricity into light energy. Light emitting diodes and is made up of a PN junction as a normal diode, also has one-way electric conductivity. When the light emitting diode with forward voltage, injected from p to n holes and n into p-electronic, in the vicinity of PN junction within a few microns respectively with n electrons and p-holes combined, resulting in spontaneous emission of fluorescence. Different semiconductor materials, electrons and holes in the different energy States. When electron and hole composite, how many different releases of energy, release more energy, the shorter the wavelength of the light emitted. Commonly used are red, green or yellow light diode. Light emitting diode's reverse Breakdown voltage is greater than 5 kV. It is to the v-I characteristic curve is very steep, it must be used with series resistor to control the current through the diode.