Photoelectrons are electrons that are emitted from a material when it absorbs light or electromagnetic radiation. This process occurs in phenomena such as the photoelectric effect, where photons, the particles of light, transfer their energy to electrons, allowing them to escape from the surface of a material, typically a metal. The energy of the emitted photoelectrons depends on the frequency of the incoming light. Higher frequency light, like ultraviolet or X-rays, can release more energetic photoelectrons compared to lower frequency light, such as visible light. This principle is fundamental in various applications, including solar cells and photodetectors.