How do LED lights work?
The full form of LED is Light Emitting Diode, which in Bengali would be Light-Emitting Diode. Generally, these lights are used in almost all places, including homes, offices, courts, schools and colleges, which are more efficient and energy-efficient than the previous conventional electric bulbs and energy bulbs. So today we will learn how this LED bulb works.
A diode is an electronic component with two terminals. The main function of a diode is to allow electricity to flow in one direction and to block the flow of electricity in the opposite direction. (The picture above shows a picture of a diode)
History of the invention of LED
The first LED was invented by Soviet scientist Oleg Losev in 1927. However, 20 years earlier, in 1907, English engineer Henry Joseph Round discovered electroluminescence. Electroluminescence is a phenomenon in which a substance emits light when an electric current is passes through it. It was a surprising discovery at the time. Losev's LED was not used for the next two decades due to its inefficient semiconductor properties. In 1961, James R. Beard and Gary Pittman, working at Texas Instruments in Dallas, Texas, invented an infrared light-emitting diode built on a GaAs substrate, the first practical LED. Their successor, TI or Texas Instruments, created the first commercial LED product.
How LED Works
LED's full name in English is Light Emitting Diode, which means that is, a type of diode that emits light.
Fig : LED Light
Now the question is what is a diode?
Fig : Different parts of LED
LED is a P-N junction diode. A P-type semiconductor and an N-type semiconductor are combined to form a P-N junction diode. A P-type semiconductor has more positive (+) charge and an N-type semiconductor has more negative (-) charge. That is, in P type semiconductor, there are fewer electrons or there is a deficiency of electrons, resulting in the formation of holes or pits in that place and these holes or pits are called positive charge carriers. On the other hand, in N type semiconductor, there are more electrons or negative charges, so it is called negative charge carriers.
In a P-N junction diode, the p-type semiconductor and the n-type semiconductor are located close to each other, so the opposite charges between the two diodes attract each other, causing the charges to combine with each other and annihilate. Then, a charge-free space is created between the two semiconductors, which is called the depletion layer of the P-N junction. Then when the P-N junction diode is connected to a battery in forward bias, the positive charge of the battery repels and pushes the positive charge of the diode away And the negative charge of the battery repels the negative charge of the diode and pushes it away, causing the positive charges to combine with each other and annihilate. As a result, photon particles are emitted from here in the form of electromagnetic radiation. We see countless such photon particles together as light. This is how an LED light works.
Below is the color of light an LED will emit based on the semiconductor material and wavelength:
Different colors of LEDs
The color of light an LED produces depends on the semiconductor used in the LED and the band gap of that semiconductor. The side of the semiconductor where there are more electrons or negative charges is called the conduction band and the side where there are more holes or positive charges is called the valence band. The gap between the valence band and the conduction band is called the forbidden energy gap or band gap. If the band gap of a semiconductor is high, light of shorter wavelength will be produced, and if the band gap is low, light of longer wavelength will be produced.
Color Wavelength Semiconductormaterial
Infrared >760nm Gallium arsenide
( GaAs )
Aluminum gallium
arsenide
( AlGaAs )
Red 610 < 760 Aluminum gallium
nm arsenide
( AlGaAs )
Gallium arsenide
Phosphide
( GaAsP )
Aluminum Gallium
Indium Phosphide
( AlGaInP )
Gallium Phosphide
( GaP )
Orange 590 < 610 Gallium arsenide
nm Phosphide
( GaAsP )
Aluminum Gallium
Indium Phosphide
( AlGaInP )
yellow 570 < 590 Gallium Phosphide
( GaP )
Green. 500 < 570 Indium gallium nitride
( InGaN ) /
Gallium nitride ( GaN )
Gallium Phosphide
( GaP )
Aluminum Gallium
Indium Phosphide
( AlGaInP )
Aluminum gallium
phosphide
( AlGaP )
Blue 450 < 500 Zinc selenide
( ZnSe )
Indium gallium
nitride
( InGaN )
Silicon Carbide
( SiC )
Purple 400 < 450 Indium gallium
nitride
( InGaN )
Light Multiple Dual Blue /
Purple types Red LED,
Blue with red
phosphor
Or White
with purple plastic
ultra < 400 Diamond ( 235
violet nanometers )
Boron nitride
Aluminum nitride
( AlN )
Aluminum Gallium
Nitride
( AlGaN )
Aluminum Gallium
Indium Nitride
( AlGaInN )
White Broad Blue diode with
Specturm yellow phosphor
or
violet/UV diode
with multi- colored
Phosphor
Use of LED lights
LED is notable in various fields of the present world. For example:
1. The displays of mobile phones, TVs, laptops, computers, etc. are made of LEDs.
2. LED lights are used for lighting in homes, offices, courts, schools, colleges, etc.
3. LED is used in the displays of any machine in various factories.
4. LED lights are used in traffic signals.
5. LEDs are used in the headlights of various vehicles on the road.
6. LEDs are used in image sensing circuits.
7. LEDs are used in silica optical communication circuits. 8. LEDs are used in fiber optical cables.
Environmental Impact of LED
Among the many advantages, some disadvantages of LED lights can be noted. For example: White LED emits more light than incandescent lights, which can cause harm to humans and other animals. The light of LED lights attracts various types of insects, insects, etc This can disrupt the food web. In addition, LED lights near the beach, especially bright blue and white LEDs, can confuse baby turtles. As a result, they come to the shore, which attracts various birds of prey such as hawks, eagles, etc., which in turn causes the baby turtles to become prey, leading to the extinction of various species of turtles. In addition, LED lights are used in traffic signals. Since LED lights produce less heat than incandescent lights, they can become covered in ice in winter, which can lead to various accidents on the road.
No comments