Efficient photoluminescence from Cu2+ doped ZnSe/ZnS core-shell quantum dots in silicate glass

Abstract

As a nontoxic and harmless photoelectric material, ZnSe quantum dots (QDs) have a broad application prospect. Incorporation of ZnSe QDs into glass provides a stable and robust substrate for QDs, but the low fluorescence efficiency of ZnSe QDs in glass limits their application. In this work, ZnSe/ZnS core-shell structure QDs is prepared in silicate glass by melt quenching and subsequent heat treatment, which is evidenced by XRD, TEM and Raman results. The surface defects of ZnSe QDs are passivated by the ZnS shell, which enhanced the luminescence of ZnSe QDS and increased the PL quauntum yeilds (PLQY) to 1.2%. With the introduction of Cu2+, two PL spectra around 500 nm and 650 nm appear simultaneously. The PL spectrum at 500 nm shows obvious size dependence, which is due to the energy transfer between ZnSe QDs and the D orbital of Cu2+, while the spectrum at 650 nm is attributed to a deeper defect. With the increase of heat treatment temperature and Cu2+ concentration, the defect luminescence gradually weakened and PLQY further increased to 4.62%.