文摘
Intentional inclusion of manganese ions (Mn2+) into colloidal quantum dots (CQDs) with precise positioning at a substitution lattice site provides a way to explore the interaction between photogenerated species (exciton, electron, hole) and Mn2+ spin states. We investigated the influence of Mn2+ impurity on the optical properties of CdTe/CdSe CQDs. Host CQDs exhibit a quasi-type-II characteristic, with asymmetric delocalization of the carriers over the entire core/shell structure. Mn2+ ions were precisely embedded either at the core or at the shell, using controlled layer-by-layer growth. Optical measurements carried out at cryogenic temperatures revealed a change in radiative lifetime, induced circular polarization, and energy split of exciton band-edge emission in the absence of an external magnetic field, when the Mn2+ ions were situated within the core. The results suggest the existence of a significant hole鈥揗n2+ exchange interaction and demonstrate a way to control band-edge optical properties in confined systems.