When it comes to LED lighting, people just trust it to work. Most people don’t even know what LED stands for! LED stands for light-emitting diode and they are the standard lighting sources of many our daily use items like calculators, stereos, microwaves, and traffic lights. These small lights can produce many colours including red, orange, yellow, green, blue, pink, purple, and white. The main advantage of LEDs is that they outlast incandescent bulbs by thousands of hours. They are essentially tiny light bulbs that fit together on an electrical circuit, they don’t have a filament that burns out, and they don’t get too hot, which makes them last so much longer.
What are LEDs?
To understand how LEDs work, we should go through what diodes are. Diodes are the simplest forms of semiconductors, which is a material that conducts electrical currents in varying degrees. In LEDs, the conductor material is generally aluminum-gallium-arsenide which has had atoms of other materials added to it (called doping), causing it to become more conductive.
A diode includes a section of N-type material bonded with a P-type material with electrodes on each end. The electricity in this arrangement flows in one direction. A depletion zone is caused when no voltage is applied to the diode while the electrons from the N-type fill holes from the P-type along the junction between the layers of the materials. When you get electrons moving from the N-type to the P-type area, the holes move in the opposite direction, which gets rid of the depletion zone. To get a light to emit, you actually have to increase the depletion zone by running the current in the opposite direction. Quite simply, this means when you connect the P-type side to the negative end of the circuit and the N-type side to the positive end, the depletion zone increases and you get light!
How LEDs work
The most basic units of light are formed from photons, what are small particle packets that have momentum and energy, but have no mass. When electrons move, the photons are released. In atoms, the electrons move around the nucleus in an orbital fashion, each electron has a different amount of energies, depending on their position in their orbital rotation. Electrons that orbit farther away from the nucleus generally have greater energy than electrons that orbit closer to the nucleus.
In visible LEDs, like the ones you see in traffic lights or your digital clock, there is a wider gap between the conduction band and the lower orbital electrons in the material. The colour of the LED is determined by the gap size and the frequency of the photon. LEDs can be made to shine in ultraviolet, infrared, or any colour of the visible spectrum, depending on which material it’s built from. LEDs are great because they are durable, efficient, and can have a lifetime of more than 50,000 hours!