Zn–CIS cores may largely remain even after ZnS shell growth. This could be the reason why the QYs of Zn– CIS/ZnS are much lower than those of CIS/ZnS and Cd–CIS/ZnS. However, based on PL decay, it is hard to explain why the QYs of Cd–CIS/ZnS are relatively lower than those of CIS/ZnS. Probably other factors (e.g., lattice mismatch introduced by Cd between Cd– CIS and ZnS for the formation of trap states in ZnS shell) need to be considered. In spite of the relatively lowered QYs, both Cd–CIS/ZnS and Zn–CIS/ZnS outweigh CIS/ZnS in PL wavelength tuning.