Understanding LED Technology: Functionality and Advantages
LED Technology
A Light-Emitting Diode, also known as an LED, is a semiconductor device that emits incoherent light when a reduced spectrum is polarized directly through the PN junction, and an electric current circulates.
This phenomenon is a form of electroluminescence.
The color depends on the semiconductor material used in the construction of the diode and may vary from ultraviolet, through the visible spectrum, to infrared.
Light-emitting diodes that emit ultraviolet light are also called UV LEDs (Ultraviolet Light-Emitting Diodes), and those that emit infrared light typically receive the designation of IREDs (Infra-Red Emitting Diodes).
Physical Functioning
In semiconductor materials, when an electron goes from the conduction band to the valence band, it loses energy. This lost energy, when passing an electron from the conduction band to the valence band, is expressed as a photon or other form of energy (heat, for example). This will depend mainly on the type of semiconductor material.
When a semiconductor diode is biased directly, the gaps of the p-zone move to the n-zone, and the electrons of the n-zone move to the p-zone. Both movements comprise the current that flows through the diode.
If electrons and holes are in the same region, they can recombine. That is, electrons can move to “fill” gaps, “falling” from a lower energy level to another more stable one. This process emits a photon with a frequency band in direct “bandgap” semiconductors, with energy corresponding to the forbidden band.
That does not mean that in other semiconductors (indirect “bandgap” semiconductors) there is no emission in the form of photons. However, these emissions are much more likely in direct bandgap semiconductors (such as gallium nitride) than in indirect bandgap semiconductors (like silicon).
Spontaneous emission, therefore, will not be produced substantially in all diodes. It is only visible as visible light in LEDs, which are available with special construction to avoid radiation being reabsorbed by the surrounding material, and the energy of the forbidden band coincides with that corresponding to the visible spectrum.
In other diodes, the energy is released mainly as heat, ultraviolet, or infrared radiation.
If the diode releases energy in the form of ultraviolet radiation, this radiation can be used to produce visible radiation by fluorescent or phosphorescent substances that absorb the ultraviolet radiation emitted by the diode and subsequently emit visible light.
Symbolic Representation
(P) Cathode or K (n) The symbolic representation of the LED semiconductor device is commonly encapsulated in an indoor plastic, offering greater resistance than the glass usually used in incandescent lamps. Although plastic can be colored for aesthetic reasons, it does not influence the color of the light emitted.
Usually, an LED light source is composed of different parts, which is why the pattern of intensity of light emitted can be quite complex. To get good light intensity, one must choose the current going through the LED. It must be remembered that the operating voltage ranges from 1.8 to approximately 3.8 volts (related to the manufacturing equipment and color of light emitted), and the range of intensities varies depending on the application.
Typical values of direct current polarization of an LED range from 10 to 40 mA.
In general, LEDs tend to have better efficiency the lower the current that flows through them. Their operation is optimized by seeking a compromise between the light intensity to produce (higher intensity with higher current) and efficiency (higher efficiency with lower current).
The first LED that emitted in the visible spectrum was developed by General Electric engineer Nick Holonyak in 1962.
*A photon is the mediating particle of the electromagnetic interaction. Photons are associated with any electromagnetic radiation.
Advantages of LED Technology
The advantages of this technology are numerous:
- With LED technology, there is lower heat dissipation. This is because the filament emits light across the visible spectrum, with the diffuser filtering to allow only the required color, and the rest of the spectrum is transformed into heat. In contrast, the LED emits monochromatic light directly in the wavelength of the required color, so there is no transformation of light into heat.
- This difference in light emission from the glow over the filter and LED makes it more efficient because all the light emitted by the light source is used in the lighting point.
- The lifespan of incandescent light is 6,000 hours, while the LED can reach up to 100,000 hours, i.e., 17 times higher.
- High levels of flow intensity and direction.
- Significant estuary for many different design options.
- High efficiency, energy saving.
- White light.
- All colors (460 nm to 650 nm).
- Low voltage requirements and consumption.
- High resistance to shock and vibration.
- No UV radiation.
- Can be easily controlled and programmed.
- Different forms of radiation with different angles.