Doping Cu(I) ions into CdS/ZnS core/shell nanocrystals through a cation exchange strategy
The optical properties of doped semiconductor nanocrystals (NCs) are strongly affected by the dopant position inside the host lattice. However, it is still unexplored to control the dopant position in the Cu(I) doped core/shell semiconductor NCs due to high ionic mobility of Cu(I) ions at the doping temperature. In this paper, we report the synthesis of Cu(I) ions-doped CdS/ZnS core/shell NCs via a cation exchange strategy. During the synthesis, the exciton emission of CdS NCs is reduced and the dopant emission becomes intensified as the doping level is increased from 0 to 1.1%, and the PL profile of the final product is very similar to that of uncoated CdS:Cu(I) NCs. Such an optical change is very different from that observed in the products synthesized by using a conventional method, in which no exciton emission of CdS NCs is observed. During the Cu(I) doping process, the variation of the dopant emission may arise from the change of the dopant position from the outside ZnS shell to the inside CdS core in the CdS/ZnS core/shell NCs. The deduction can be further verified by the optical change by direct heating less amount of Cu(I) doped CdS/ZnS NCs in a non-coordinating solvent. This work offers a cation exchange strategy for fabricating Cu(I) doped core/shell NCs with tuning dopant position, which will open rich opportunities for tuning the optoelectronic properties of Cu(I) doped semiconductor NCs.