Published: 18th Jan, 2024
Context
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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