LIGHT
EMITTING DIODE – SCI & TECH
News:
What is light-emitting
diodes and why are they prized as light sources? | Explained
What's
in the news?
●
In October 2014, the Royal Swedish Academy
of Sciences issued a statement in which it said, “Incandescent light bulbs …
lit the 20th century; the 21st century will be lit by LED lamps.”
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The occasion was the awarding of the Nobel
Prize for physics for that year, for an achievement that paved the way for
light-emitting diodes (LEDs) to succeed the incandescent bulbs and fluorescent
lamps of previous centuries as the world’s light-source of choice.
Key
takeaways:
●
Even before Haitz’s law, researchers prized LEDs because they were more
efficient than incandescent bulbs and fluorescent lamps.
Light
Emitting Diode:
●
An LED is a diode that emits light. Inside the diode’s p-n junction, the
electrons have more energy than the holes. When an electron meets and occupies
a hole, it releases energy into its surroundings.
●
If the frequency of this energy is in the
visible part of the electromagnetic spectrum, the diode will be seen to emit
light. The overall phenomenon is called electroluminescence.
●
In LEDs, the energy emitted when an
electron and a hole recombine is the energy
of the band gap.
Colour
of LED:
●
The colour of the light emitted by the LED
depends on the energy bandgap of the semiconductor material used.
●
LEDs can produce all three primary colours — red, green and blue — different
LEDs can be combined on a display board to produce a large variety of colours.
Advantages
of LEDs:
1.
Energy Efficiency:
●
LEDs are more efficient than incandescent
bulbs and fluorescent lamps.
●
They convert a higher percentage of
electrical energy into light.
●
Together with their greater durability and
light contrast, LEDs’ lead to higher cost savings and less material waste.
2.
Long Lifespan:
●
LEDs have a much longer lifespan and
durability compared to conventional bulbs.
●
They can last up to 25 times longer, which
means fewer replacements and reduced maintenance costs over time.
3.
Instantaneous Lighting:
●
LEDs light up instantly without any
warm-up time.
●
They reach their full brightness
immediately, which is particularly useful in applications where quick and
frequent switching is required.
4.
Compact Size:
●
LEDs are compact and can be made in very
small sizes.
●
This makes them versatile and allows for
innovative lighting designs and applications where space is limited.
Applications:
1.
Lighting:
●
Residential lighting, Commercial lighting,
Automotive Lighting, Dashboard and instrument panel lighting, Backlighting for
LCD screens in smartphones, tablets and laptops.
2.
Electronic Displays:
●
LED TVs and monitors, Digital billboards
and signage, Information displays (public transportation, airports).
●
Traffic Signals and Signs: Pedestrian
crossing signals, Road signs and signal boards.
3.
Indicator Lights:
●
Power indicators on electronic devices,
Status indicators on appliances and equipment.
4.
Medical Applications:
●
Surgical lights, Phototherapy for medical
treatments.
5.
Horticultural Lighting:
●
Grow lights for indoor farming and plant
cultivation, Greenhouse lighting.
6.
UV-C Disinfection:
●
UV-C LED lights for disinfection and
sterilisation purposes, Water and air purification systems.