Why are LEDs diodes?

davetrousers

Just wondering if anyone knows why LEDs need to be diodes. Could you not have a Light Emitting 'device' that doesn't need the electricity to flow through it in one way only?

Don't be smart and say a conventional filament bulb, lol.

fwor

The reason why is that the light is produced at the junction between two different materials (termed the p-n junction), where there is a "band gap" between electrons at different energy levels.

Each electron that makes the transition between these two levels loses a specific amount of energy, which corresponds to a specific wavelength of light (although in reality this is actually a range of wavelengths).

If you look at the diagram in the Physics section of the wiki, you'll see why it only works in one direction, which also explains why it operates as a diode:

http://en.wikipedia.org/wiki/LED

A conventional bulb works purely by resistive heating of the filament, which is much less efficient, as it's not possible to do that without losing a lot of energy at wavelengths other than visible light.

Strider590

davetrousers wrote: »

Just wondering if anyone knows why LEDs need to be diodes. Could you not have a Light Emitting 'device' that doesn't need the electricity to flow through it in one way only?

Don't be smart and say a conventional filament bulb, lol.

2 LED's stuck together backwards in parallel?