Light Emitting Diodes or LED s are semiconductor diodes that help current flow in one direction. The diode is formed by two different elements joined together to form a p-n junction as in the following figure. In a p-n junction, the P side contains “holes” with abundance of positive charge and devoid of free electrons while the N side contains excess negatively charged electrons.
p-n junction LED picture:
When a forward voltage is applied to the semiconducting element forming the p-n junction, electrons move from the N element towards the P element and holes move towards the N element. Electrons and holes combine with each other near the junction. This results in emission of energy as light rays.
