According to abbreviationfinder, An LED or light-emitting diode is a semiconductor device (diode) that emits incoherent light with a reduced spectrum when its PN junction is directly polarized and an electric current flows through it. This phenomenon is a form of electroluminescence. The color depends on the semiconductor material used in the construction of the diode and can vary from ultraviolet, through visible, to infrared. Light-emitting diodes that emit ultraviolet light are also called UV LEDs (ultraviolet light: “ultraviolet light”) and those that emit infrared light are called IREDs (InfraRed Emitting Diode: “infrared radiation”).
The Spanish name comes from the English acronym LED (Light-Emitting Diode: ‘light-emitting diode’).
The first led was developed in 1927 by Oleg Vladimirovich Losev, however it was not used in industry until the 1960s. They could only be built in red, green and yellow with low light intensity and limited their use to remote controls (remote controls) and electrical appliances to mark on and off. At the end of the 20th century, ultraviolet and blue LEDs were invented, which led to the development of the white LED, which is a phosphor- coated blue light LED. that produces a yellow light, the mixture of blue and yellow produces a whitish light called “moonlight” achieving high luminosity (7 unit lumens) with which its use in lighting systems has been expanded….
The physical operation consists in that, in semiconductor materials, an electron, when passing from the conduction band to the valence band, loses energy; This lost energy can manifest itself in the form of a detached photon, with a random amplitude, direction and phase. Whether that energy lost when an electron passes from the conduction band to the valence band is manifested as a detached photon or as another form of energy (heat for example) will depend mainly on the type of semiconductor material. When a semiconductor diode is directly biased, the holes in the p zone move toward the n zone and the electrons from zone n to zone p; both displacements of charges constitute the current flowing through the diode.
If the electrons and holes are in the same region, they can recombine, that is, the electrons can “occupy” the holes, “falling” from a higher energy level to a lower, more stable one. This process often emits a photon in direct bandgap semiconductors with the energy corresponding to its bandgap (see semiconductor). This does not mean that the other semiconductors (indirect bandgap semiconductors) do not produce photon emissions; Nevertheless,
Spontaneous emission, therefore, does not occur notably in all diodes and is only visible in diodes such as visible light LEDs, which have a special constructive arrangement in order to prevent radiation from being reabsorbed by the surrounding material., and an energy of the forbidden band coinciding with that corresponding to the visible spectrum. In other diodes, energy is released primarily in the form of heat, infrared radiation, or ultraviolet radiation. In the event that the diode releases energy in the form of ultraviolet radiation, it is possible to take advantage of this radiation to produce visible radiation, using fluorescent or phosphorescent substances. that absorb the ultraviolet radiation emitted by the diode and subsequently emit visible light.
The semiconductor device is commonly encapsulated in a plastic cover that is higher resistance than the glass that is usually used in incandescent lamps. Although the plastic may be colored, it is only for aesthetic reasons, as this does not influence the color of the light emitted. Usually an LED is a light source composed of different parts, which is why the intensity pattern of the emitted light can be quite complex.
To obtain good light intensity, the current through the LED must be chosen well; To do this, it must be taken into account that the operating voltage ranges from 1.8 to 3.8 volts approximately (which is related to the material of manufacture and the color of the light it emits) and the range of intensities that must circulating through it varies according to its application. Typical values of direct current of polarization of a current led are between 10 and 40 mA. In general, LEDs tend to have better efficiency the lower the current that circulates through them, which is why, in their optimized operation, a compromise is usually sought between the light intensity they produce (the greater the greater the intensity they produce. circulates through them) and efficiency (the higher the lower the intensity that circulates through them). The first LED to emit in the visible spectrum was developed by General Electric engineer Nick Holonyak in 1962.