Cation exchange assisted synthesis of ZnCdSe/ZnSe quantum dots with narrow emission line widths and near-unity photoluminescence quantum yields.

Quantum dots with narrow emission line width have persistently received attention for their applications in biological imaging, lasers and next-generation displays. We herein report a cation exchange assisted shelling approach changing the starting CdSe emitting cores into new ZnCdSe alloy emitting cores and finally ZnCdSe/ZnSe core/shell QDs. The resulting ZnCdSe/ZnSe QDs exhibit an emission line width as narrow as 17.1 nm with a near-unity photoluminescence quantum yield and a single emission channel. We anticipate that our study on a cation exchange assisted synthetic route for controlling the emission line widths of the QDs could be extended to high-quality green and blue ones beyond currently achieved.