What are LEDs?
LEDs are Light Emitting Diodes (semiconductors). LEDs emit light when a small current is applied in the forward direction. their chip is basically made of a semiconductor material doped with impurities creations P.N junctions. LEDs have polarity, being the Anode the positive lead (the longer lead), and the Cathode the negative lead (the shorter lead), reason why they only work when bias forward.
The electroluminiscence happens when, stimulated by a forward voltage, the negative electrical charges (electrons) and the positive electrical charges (holes) are attracted to the junction zone and start recombining, releasing energy as photons as shown in this figure:
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LEDs are components that, according to the chemical elements combined in their composition (like AlGaInP, GaAs, GaInN, GaP, etc.), can produce a wide range of wavelengths or colors, from the IR or Infra Red, going through the visible spectrum (red, orange, yellow, green, blue, and all their possible combinations), to the UV or Ultra Violete wavelength. Reason why they are so suitable on applications that need certain colors that traditional light sources can not match.
See LEDs' Advantages
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