What is LED?
An LED (Light Emitting Diode) is a semiconductor device that emits light when an electric current passes through it. It is an advanced form of lighting technology that has become extremely popular due to its efficiency, durability, and low power consumption. Unlike traditional bulbs, LEDs do not have filaments that burn out and do not get excessively hot.
Structure of LED
The structure of an LED consists of several key components:
- Semiconductor Material: The core is made of materials like Gallium Arsenide (GaAs), Gallium Phosphide (GaP), or Gallium Nitride (GaN).
- P-N Junction: The point where the positive (p-type) and negative (n-type) materials meet, generating light.
- Encapsulation: The LED chip is protected by a plastic or epoxy resin casing that also acts as a lens.
- Leads (Anode & Cathode): Two terminals for current flow; the longer lead is the anode, and the shorter is the cathode.
History of LED Invention
The journey of LED invention spans over a century:
- 1907: Electroluminescence was first observed by H.J. Round using silicon carbide.
- 1927: Oleg Losev built the first LED-like device.
- 1961: Robert Biard and Gary Pittman created the first infrared LED.
- 1962: Nick Holonyak Jr. developed the first visible-spectrum (red) LED.
- 1990s: Shuji Nakamura, Isamu Akasaki, and Hiroshi Amano invented the blue LED, enabling white LED technology.
How Does an LED Work?
LEDs work on the principle of electroluminescence:
- When voltage is applied, electrons and holes move towards the p-n junction.
- They recombine at the junction, releasing energy in the form of photons.
- The color of the light depends on the material's bandgap.
Advantages of LEDs
- High energy efficiency
- Long lifespan (25,000–50,000 hours)
- Low heat generation
- Environmentally friendly (no toxic elements)
- Compact size and flexible designs
- Instant on/off performance
Applications of LEDs
- Electronic indicators and displays
- Automotive and street lighting
- Television and monitor displays
- Medical devices and surgical lights
- Traffic signals and signage
- Decorative and architectural lighting
Conclusion
LED technology has revolutionized lighting with its efficiency, long life, and eco-friendly nature. From simple indicator lights to complex lighting systems, LEDs play a vital role in modern life and continue to advance with new innovations.