Current methods of the synthesis of luminescent semiconductor nanocrystals for biomedical applications

Abstract

The most widespread methods for the colloidal synthesis of highly luminescent CdSe, CdS, ZnSe and other AIIBVI core-shell colloidal quantum dots (QDs) are reviewed. Advantages and disadvantages of the currently developed one-pot QD synthesis as compared to the classical multistage approaches are discussed. The noninjection one-pot method starts with the growth of metastable magic-size seeds; their subsequent recrystallization ensures slow, controllable growth of highly monodisperse, defect-free core nanocrystals of desired sizes and shapes. Subsequent formation of a shell out of a semiconductor with a wider bandgap yields gradient core-shell QDs with a smooth potential barrier for electrons and holes, without strains or interfacial defects, and, as a consequence, a luminescence quantum yield (QY) approaching 100%. This approach can also be applied to other semiconductor systems to cover the broad spectral range from the near-ultraviolet (UV) to infrared (IR) regions of the optical spectrum. These nanocrystals may replace fluorescent organic dyes and rare-earth luminophores in their current applications.