What are light-emitting diodes and why are they prized as light sources?

• In 2014, the Royal Swedish Academy of Sciences predicted the dominance of Light-Emitting Diodes (LEDs) in the 21st century, marking a shift from traditional lighting sources.

Understanding Diodes

• Diodes are electronic components allowing current flow in only one direction.
• They consist of a p-n junction, where electrons move from the n-type material (its primary charge-carriers are electrons) to the p-type material (its primary charge-carriers are holes), creating a one-way current flow.
• The diode has an anode and a cathode, connected to the p-type and n-type materials, respectively.

Evolution to LEDs

• An LED is a diode emitting light through electroluminescence.
• The p-n junction in LEDs allows electrons with more energy than holes to release light upon recombination.
• The band gap, representing the energy difference between electron levels, determines the emitted light's frequency.

Significance of the Band Gap

• Particles such as electrons exhibit distinct energy levels, and the band gap establishes the energy range within which electrons are capable of flowing.
• An electric field applied to a material can provide electrons with extra energy to overcome the band gap.
• In LEDs, the band gap plays a crucial role in determining the energy released during the process of electron-hole recombination.

LED Color Production

• LEDs can produce red, green, and blue colours, allowing a combination for various hues.
• Despite challenges, gallium nitride enabled the development of blue LEDs, accomplished by Japanese researchers in the late 1980s, ultimately earning them the 2014 Nobel Prize.

Advantages of LEDs

• Moore's law and Haitz's law predict exponential growth and efficiency improvements in LEDs over time.
• LEDs are more energy-efficient, durable and cost-effective than incandescent bulbs and fluorescent lamps.
• Applications range from consumer electronics to industrial use, showcasing their versatility and impact on energy conservation.

Ongoing Innovations and Future Prospects

• Ongoing research explores new materials like perovskites for more efficient LEDs.
• Organic LEDs and embedded LEDs in skin represent emerging technologies expanding LED applications.