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چکیده
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In this study, by a UV-assisted chemical approach, ZnSe:Cu and ZnSe:Cu/ZnS core/shell quantum dots(QDs) were fabricated with different contents of Cu dopant. UV radiation was used as a catalyst for sodium thiosulfate (Na2S2O3) reaction to produce S species. Next, the photoluminescence (PL) of the mentioned QDs was studied and the effect of ZnS shell formation on the core QDs, lattice strain, crystallites size and also the effect of Cu dopant concentration on their PL intensity were investigated. Results showed that photoluminescence is sensitive to lattice strain and crystallites size; so that with the reduction (or increase) of the lattice strain, the intensity of PL emission generally increases (or decreases). Also, quantum dots with larger crystallite size had totally higher PL intensity. It was shown that, the formation of the ZnS shell on the core QDs leads to a general decrease in the trap states emission intensity and an improvement in the band edge emission. Also, increasing of copper impurity content, reduced the trap states emission intensity and the band edge. The highest band edge emission was devoted to ZnSe and ZnSe/ZnS QDs and the highest emission from trap states was devoted to ZnSe and ZnSe:Cu(0.1%)/ZnS QDs, in which considering the stability, core/shell QDs for use in photoluminescence systems and LEDs are preferable.
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