What is LED?
A light-emitting diode(LED) is a semiconductor light source When a light-emitting diode is forward biased (switched on), electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence.
Electroluminescence (EL) is an optical phenomenon and electrical phenomenon in which a material emits light in response to the passage of an electric current or to a strong electric field.
LEDs were Introduced as a practical electronic component in 1962, early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet and infrared wavelengths, with very high brightness and the colour of the light depends upon the wavelength of the light emitted, and thus on the band gap energy of the materials forming the p-n junction (corresponding to the energy of the photon) or by the energy gap of the semiconductor.
LEDs development began with infrared and red devices made with gallium arsenide. Advances in materials science have enabled making devices with ever-shorter wavelengths, emitting light in a variety of colours.
LEDs are often small in area (less than 1 mm2), and these Solid state devices such as LEDs are subject to very limited wear and tear if operated at low currents and at low temperatures. Typical lifetimes quoted are 25,000 to 100,000 hours but heat and current settings can extend or shorten this time significantly
LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved robustness, smaller size, and faster switching. LEDs powerful enough for room lighting.
Light-emitting diodes are used in applications as diverse as replacements for aviation lighting,automotive lighting (particularly brake lamps, turn signals and indicators) as well as in traffic signals.
LEDs have allowed new text, video displays, and sensors to be developed, while their high switching rates are also useful in advanced communications technology.
Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players, and other domestic appliances.