Photoluminescence is a research area within the field of materials science and optical physics that involves the study of the emission of light from a material after it has absorbed photons. This phenomenon occurs when a material is excited by a light source (such as a laser) and then emits light at a different wavelength as it returns to its ground state. Photoluminescence is commonly used in various applications such as semiconductor devices, solar cells, and biological imaging. Researchers in this field study the mechanisms and properties of photoluminescence to better understand the behavior of materials and develop new technologies.