Enhancement of blue fluorescence on the ZnSe quantum dots doped with transition metal ions

Blue-emitting ZnSe quantum dots (QDs) doped with different transition metal (TM) ions, such as Cd2+, Cu2+, Mn2+ and Fe2+ were synthesized by controlling the nucleation-doping process. All QDs not only remain in blue or near blue emission region but also greatly enhance the photoluminescence (PL) efficiency after doping these four divalent ions. Among the four ion-doped ZnSe, ZnSe doped with Fe2+ reaches the highest quantum yield (QY) of 50.2% and increases 35.8-fold compared with undoped ZnSe. In the meanwhile, 50.2% is much higher than the published QY value for aqueous doped ZnSe QDs. A possible nucleation-doping mechanism is that these TM ions occupy the surface and interior of ZnSe QDs. Doped ZnSe QDs can be a prominent candidate for constructing blue-light-emitting LED, blue laser diodes, and so on.

► A series of divalent transition metal ion-doped ZnSe quantum dots.
► All QDs emitting blue or near blue light under UV excitation.
► Fe2+-doped ZnSe quantum dots with the highest quantum yield of 50.2%.
► The mechanism of higher quantum yield was clearly explained