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Luminescence properties of Cu and Cu,Al doped ZnS quantum dots

Free-standing ZnS:Cu and ZnS:Cu,Al quantum dots were prepared in the aqueous medium from readily available precursors. The construction, morphology and luminescence properties of the ZnS:Cu and ZnS:Cu,Al quantum dots were evaluated by XRD,TEM and photoluminescence spectra. The average particle size was calculated using the Scherrer formula to be 5nm, which is also observed from HRTEM image. In PL spectra, 0.7% Cu and 0.4% Cu -doped ZnS:Cu quantum dots have emission peak around 470 nm and 500 nm, which attributed to the transition from the shallow donor level (sulfur vacancy) to the e level and t2 level of Cu2+ respectively. And PL spectra of ZnS:Cu,Al quantum dots is similar with the PL of ZnS:Cu quantum dots, but the luminescence intensity of quantum dots ZnS:Cu,Al increase, which arise from that Al 3+ ions as co-activated enhance donor level.