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The Evolution and Advantages of Light-Emitting Diodes (LEDs)


The emergence of light-emitting diodes (LEDs) as the lighting choice of the 21st century, recognized by the Nobel Prize in Physics in 2014, marks a significant shift from traditional incandescent bulbs and fluorescent lamps

Diodes: Foundations of LED Technology

What are diodes?

  • A diode, a fundamental electronic component, allows the flow of current in only one direction through a p-n junction.
  • This junction comprises a p-type material with positive charge-carriers (holes) and an n-type material with negative charge-carriers (electrons).

How does a diode work?

  • An electric field applied across the diode encourages electrons to flow from the n-side to the p-side, creating an electric current.
  • This one-way flow is crucial in electronic circuits.

LEDs: Harnessing Light Emission

What is an LED?

  • An LED is a diode that emits light through
  • In the p-n junction, electrons, having more energy than holes, emit light when occupying a hole.
  • The band gap, the energy difference between electron energy levels, determines the emitted light's frequency.

What is the band gap?

  • The band gap, crucial in LED functioning, represents the energy required for electrons to jump from lower to higher energy levels.
  • In LEDs, the energy released during electron-hole recombination corresponds to the band gap, determining the emitted light's color.

What colors can an LED produce?

  • By carefully selecting materials for the p-layer and the n-layer, researchers engineer LEDs to emit visible light.
  • LEDs can produce red, green, and blue, allowing the creation of a spectrum of colors on display boards and various applications.

Need for LEDs:

Efficiency and Advantages

Why are LEDs prized?

  • Even before Haitz's law, LEDs were valued for surpassing incandescent bulbs and fluorescent lamps in efficiency.
  • Haitz's law predicts a 10x drop in cost and a 20x increase in light output every decade.
  • LEDs provide up to 300 lumens per watt, compared to incandescent bulbs' 16 lumens and fluorescent lamps' 70 lumens per watt.

Applications and Benefits

  • LEDs, with their durability and energy efficiency, find applications in diverse fields – from consumer electronics to industrial settings.
  • Their advantages include higher cost savings, less material waste, and enhanced performance in various devices, including smartphones, TV screens, and even air quality monitoring.

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