Semiconductor Electronics: Materials, Devices and Simple Circuits

Light Emitting Diode

We use light-emitting diodes, or LEDs, commonly as a standard source of light in electrical equipment. Further, it has got a broad range of applications which vary from the mobile phone we use every day to big advertising billboards. Moreover, they find uses in devices to show what the time is. Similarly, we also use it to display different kinds of data. Through this article, we will look at what LEDs are and the uses as well as types of it. Thus, it will help us in getting a better understanding of light emitting diode.

light emitting diode

Introduction to Light Emitting Diode

A light releasing diode is an electric component which emits light when the electric current flows through it. Further, it is a light source which is on the basis of semiconductors.

When current passes through the LED, the electrons recombine with holes and emit light in this procedure. It is a particular kind of diode which has the same type of characteristics as the p-n junction diode.

This means that an LED enables the flow of current in its forward direction whereas it blocks the flow in the reverse direction. Further, we build light-emitting diodes through the use of a weak layer of heavily doped semiconductor material.

On the basis of the semiconductor material which we use plus the amount of doping, an LED will emit a coloured light at a specific spectral wavelength when forward biased.

LED Symbol

light emitting diode

LED Symbol

Now, we will take a look at what a LED symbol is and its demonstration was given above. If you look closely, the symbol resembles the p-n junction diode. Basically, what makes them different from each other is that the two arrows denote that the diode is emitting the light.

Light Emitting Diode Circuit

The LEDs also have a particular drop in voltage forward in cases where we use typical circuits such as a conventional diode. The drop in voltage is dependent on the current of the LED, the colour of the produced light and more.

There are different values in the drop of voltage which would range from 1.5V to 2.5 V current for 10 to 50 mA current.

Working Principle of Light Emitting Diode

The holes lie in the valence band, whereas the free electrons are in the conduction band. When there is a forward bias in the p-n junction, the electron that is a part of the n-type semiconductor material will overrun the p-n junction and join with the holes in the p-type semiconductor material.

Thus, when we talk about the holes, the free electrons are going to be at the higher energy bands. When this movement of free electron and hole occurs, there is a change in the energy level as the voltage drops from the conduction band to the valance band.

After that, the energy releases because of the motion of the electron. In standard diodes, the release of energy is in the manner of heat. However, in LED the release of energy in the form of photons will produce light energy.

We refer to this whole process as electroluminescence. Similarly, we refer to the diodes as a light-emitting diode. In LED, energy which discharges in light creates hinges on the forbidden energy gap.

We can manipulate the wavelength of the light which is generated. Thus, from its wavelength, the light colour and its visibility or cannot be controlled. We can determine the colour and wavelength of the light by doping it with multiple impurities.

Uses of Light Emitting Diode

We use LEDs in a lot of fields which includes optical communication, alarm and security systems. Further, we also use them in remote-controlled operations, robotics, and more.

Mainly, we use it in so many areas because of the long-lasting capability of it as well as the low power requirement, fast switching capacity and rapid response time. Now, we will take a look at some of the few standard uses of the light-emitting diode:

TV back-lighting

The backlight of a TV is the major power-consuming source. When we use LEDs, it offers an efficient power reduction. Similarly, when we use an LED at the TV’s edges, it is going to be a cost reduction choice.

Using LEDs directly behind the display offers much better contrast. This is why CFLs and LCDs have been replaced by LEDs in TV backlighting.

Smartphone Backlighting

LEDs help in thinning the backlight design of our smartphones and also makes it within a low cost. While the price of LED can vary as per the sizes of the display of the smartphone, the lower output voltage ensures a longer battery life.

Displays

LED display boards are common now these days and are used outdoors like storage signs, billboards, road signs, etc. In signboards which has multiple languages conveying signals, the use of more LEDs will be beneficial in terms of less power consumption.

Automotive

The automotive industry has been increasingly using LEDs. They help to save energy and make visibility clearer. Further, they come in use greatly in the back and rear of an automobile and gives better accessibility.

Moreover, it can also enhance the pedestrian’s and driver’s safety because enhanced visibility helps with it.

Dimming of lights

We also use LEDs for dimming of lights and reduce energy consumption. We can also use this dimming feature in appliances which need global dimming and local dimming.

This dimming feature is also used in Appliances where it is of two types.

Types of Light Emitting Diode

There are various kinds of LEDs which we design through the use of semiconductors. They include:

  • Miniature LEDs
  • Bi and Tri-Colour
  • High-Power LEDs
  • Flash LED
  • Alphanumeric LED
  • Red Green Blue LEDs
  • Lighting LED

FAQ on Light Emitting Diode

Question 1: Which fields use LEDs?

Answer 1: We use LEDs in a lot of fields which includes optical communication, alarm and security systems. Further, we also use them in remote-controlled operations, robotics, and more.

Question 2: Why do we use LEDs in smartphones?

Answer 2: LEDs help in thinning the backlight design of our smartphones and also makes it within a low cost. While the price of LED can vary as per the sizes of the display of the smartphone, the lower output voltage ensures a longer battery life.

Share with friends

Customize your course in 30 seconds

Which class are you in?
5th
6th
7th
8th
9th
10th
11th
12th
Get ready for all-new Live Classes!
Now learn Live with India's best teachers. Join courses with the best schedule and enjoy fun and interactive classes.
tutor
tutor
Ashhar Firdausi
IIT Roorkee
Biology
tutor
tutor
Dr. Nazma Shaik
VTU
Chemistry
tutor
tutor
Gaurav Tiwari
APJAKTU
Physics
Get Started

Leave a Reply

avatar
  Subscribe  
Notify of

Customize your course in 30 seconds

Which class are you in?
No thanks.