High quantum yield blue- and orange-emitting carbon dots: one-step microwave synthesis and applications as fluorescent films and in fingerprint and cellular imaging.

A high quantum yield (QY) is the key requirement for implementing carbon dots (CDs) in nearly all applications. In this work, blue emissive N-doped CDs with a QY of 83% and orange emissive N-doped CDs with a QY of 47% were successfully prepared using resorcinol and phloroglucin as carbon resources in formamide by one-step microwave synthesis, respectively. Formamide not only plays a role as the solvent but also takes part in the formation of the high QY CDs. It is demonstrated that the as-prepared blue- and orange-emitting N-doped CDs with a high QY can be uniformly dispersed into glue and be fabricated as CD/glue fluorescent composites for fluorescent films and fingerprint imaging. Furthermore, these CDs also show excellent cellular imaging capability.