Decoupling and Coupling of the Host-Dopant Interaction by Manipulating Dopant Movement in Core/Shell Quantum Dots

Doping through the incorporation of transition metal ions allows for the emergence of new optical, electrical, and magnetic properties in quantum dots (QDs). While dopants can be introduced into QDs through many synthetic methods, the control of dopant location and host-dopant (H-D) coupling through directional dopant movement is still largely unexplored. In this work, we have studied dopant behaviors in Mn:CdS/ZnS core/shell QDs and found that dopant transport behavior is very sensitive to the temperature and microenvironments within the QDs. The migration of Mn toward the alloyed interface of the core/shell QDs, below a temperature boundary (T_b) at ∼200 °C, weakens the H-D interactions. At temperatures higher than the T_b, however, dopant ejection and global alloying of CdS/ZnS QDs can occur, leading to stronger H-D coupling. The behavior of incorporated dopants inside QDs is fundamentally important for understanding doping mechanisms and the host-dopant interaction-dependent properties of doped nanomaterials.