Enhanced luminescence of ZnSe:Eu3 +/ZnS core–shell quantum dots

Abstract Core/shell quantum dots (QDs) show novel properties compared to conventional single QDs, such as high quantum yields, excellent photostability, good monodispersity. In aqueous solution, monodisperse and highly luminescent ZnSe:Eu 3 + /ZnS core/shell nanocrystals were synthesized by the two-step wet chemical method. Transmission electron microscopy (TEM) images of ZnSe:Eu 3 + QDs and ZnSe:Eu 3 + /ZnS core/shell QDs showed nearly monodisperse particles with size of around 2.9 nm ± 0.3 and 4.5 nm ± 0.3. X-ray powder diffraction (XRD) results show that ZnSe:Eu 3 + /ZnS QDs possess cubic zinc blende structure. The effects of the reaction time on the luminescence properties were systematically studied. From the photoluminescence (PL) spectra, it was found that the ZnSe:Eu 3 + /ZnS nanocrystals with 3-mercaptopropionic acid (MPA) capping exhibited the Eu 3 + ion related characteristic luminescence. When a larger band gap ZnS shell was deposited at the surface of the ZnSe:Eu 3 + core, luminescence of Eu 3 + ion related emission was enhanced nearly two times.