As soon as an electron meets a hole in this region, it falls into it, and repairs that chemical bond.

When an LED is hooked up to a battery, the electrons and holes flood towards the place where the two layers of the semiconductor meet. In an LED, the whole crystal junction emits light as electrons drop back to a lower level. In a neon sign, each atom emits light when an electron spontaneously falls back to its original energy level. In an LED the battery pumps up the atoms’ electrons directly. LEDs use materials that can handle the necessary levels of electricity, heat, and humidity. Those individual wavelengths appear as light of different colors. LEDs produce different colors by using various materials which produce photons at different wavelengths. When forward current is passed through the light-emitting diode, carriers (electrons and holes) move. Why does an LED emit light?Ī light-emitting diode (LED) emits light by applying a forward current to the pn junction of a compound semiconductor. Several semiconductor compounds are commonly used in production of LEDs: Gallium nitride (GaN), aluminium gallium nitride (AlGaN), indium gallium nitride (InGaN), aluminium indium gallium phosphide (AlInGaP), gallium arsenide (GaAs), and aluminium gallium arsenide (AlGaAs).

So that’s it! Basically, what happens inside an LED when it is forward biased is just similar to a regular diode, except that electrons release light instead of heat when they change energy levels. 24 What is the lifetime of LED? How does an LED work at the molecular level?Īs free electrons cross the junction and recombine with holes, electrons release energy in the form of light.

How the led works