Naphthalene is an aromatic hydrocarbon with two fused benzene rings, which has good electronic properties and high stability. They can be easily substituted with various functional groups to tune their electronic and optical properties. Naphthalene is often used as a building block for the synthesis of small molecule semiconductors because of their ability to form stable free radicals and their excellent charge transport properties. In OLEDs, naphthalene can act as a light-emitting material, while in OPVs, they can act as electron-accepting elements. Their simple structure and robust properties make them versatile in a wide range of organic electronic applications.