Light-Emitting Diode (LED Lighting)
How does it Work?
A light-emitting diode (LED) is a two-lead semiconductor light source. It looks similar to a pn-junction diode, which emits light when activated. When a fitting voltage is applied to the leads, electrons are then able to recombine with electron holes within the device releasing energy in the form of photons. The effect is called electroluminescence. The color of the light is determined by the energy band gap of the semiconductor.
Most materials used for LED production have very high refractive indices. This means that much light will be reflected back into the material at the material/air surface interface. As such, light extraction in LEDs is an important aspect of LED production, subject to much research and development.
Many believe that LED technology is new, but in fact LED history goes back over 50 years. Common uses include traffic lights, reader boards and large video screens used in event environments such as ballparks.
The advantages of LED technology are that it is an energy efficient source of light for short distances and small areas. The typical LED requires only 30-60 milliwatts to operate. Additionally, it is shockproof and very durable.
There are some disadvantages such as unreliability in outside applications where weather conditions are extreme. With future technology this problem will be resolved. The semiconductors are sensitive to damage by heat; so large heat sinks need to be used to keep powerful arrays cool. At times a fan may be needed. This adds to the cost and fans reduce some of the energy efficient advantages of LEDs. Finally, circuit board solder and think copper connections crack over time causing sections of the arrays to go out.