Exciton

An exciton is a temporary, energy-carrying particle that forms when light interacts with a material, like a semiconductor. When a photon (light particle) hits the material, it can excite an electron, giving it energy to move to a higher state. This creates a pair: the excited electron and the "hole" left behind, which is essentially a positive charge. These two stay close due to electrostatic attraction, moving together as a bound state called an exciton. Excitons play an important role in processes like solar energy conversion and light emission in devices such as LEDs.