LED

What is LED?

A light-emitting diode (LED) is a semiconductor device that emits light when an electric current flows through it. When current passes through an LED, the electrons recombine with holes emitting light in the process. LEDs allow the current to flow in the forward direction and blocks the current in the reverse direction.

Light-emitting diodes are heavily doped p-n junctions. Based on the semiconductor material used and the amount of doping, an LED will emit a coloured light at a particular spectral wavelength when forward biased. As shown in the figure, an LED is encapsulated with a transparent cover so that emitted light can come out.

LED Symbol

The LED symbol is the standard symbol for a diode, with the addition of two small arrows denoting the emission of light.

Simple LED Circuit

The figure below shows a simple LED circuit.

The circuit consists of an LED, a voltage supply and a resistor to regulate the current and voltage.

Types of LED

Below is the list of different types of LED that are designed using semiconductors:

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

How does an LED work?

When the diode is forward biased, the minority electrons are sent from p → n while the minority holes are sent from n → p. At the junction boundary, the concentration of minority carriers increases. The excess minority carriers at the junction recombine with the majority charges carriers.

The energy is released in the form of photons on recombination. In standard diodes, the energy is released in the form of heat. But in light-emitting diodes, the energy is released in the form of photons. We call this phenomenon electroluminescence. Electroluminescence is an optical phenomenon, and electrical phenomenon where a material emits light in response to an electric current passed through it. As the forward voltage increases, the intensity of the light increases and reaches a maximum.

Uses of LED

LEDs find applications in various fields, including optical communication, alarm and security systems, remote-controlled operations, robotics, etc. It finds usage in many areas because of its long-lasting capability, low power requirements, swift response time, and fast switching capabilities. Below are a few standards LED uses:

• Used for TV back-lighting
• Used in displays
• Used in Automotives
• LEDs used in the dimming of lights

Frequently Asked Questions – FAQs

What is LED?

A light-emitting diode (LED) is a semiconductor device that emits light when an electric current flows through it.

What is Light Emitting Diodes used for?

LEDs have a wide range of applications ranging from your mobile phone to large advertising billboards. They mostly find applications in devices that show the time and display different types of data.

How do LEDs work?

LEDs work on the principle of Electroluminescence. On passing a current through the diode, minority charge carriers and majority charge carriers recombine at the junction. On recombination, energy is released in the form of photons. As the forward voltage increases, the intensity of the light increases and reaches a maximum.

What is Electroluminescence?

Electroluminescence is an optical phenomenon, and electrical phenomenon where a material emits light in response to an electric current passed through it.

What are the advantages of LEDs?

LEDs consume less power, and they require low operational voltage. No warm-up time is needed for LEDs.

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