Carbon dots: mysterious past, vibrant present, and expansive future

Carbon dots (CDs) are a vibrant subset of luminescent nanomaterials exhibiting structural and physicochemical properties that make them an ideal platform for the development of biological imaging agents, optoelectronic devices, and energy conversion/storage devices. In recent years, research relating to CDs has grown exponentially, although not without controversy relating to the structure of CDs and structure–property relationships. Many historical misconceptions about CDs are slowly being resolved by approaching the synthesis and characterization of CDs with appropriate scientific rigor. This review highlights the recent advances in the synthesis and applications of CDs, paying particular attention to the association between CD structure, properties, and usage, while highlighting important new trends in CD research.