- Title
- Optical properties of water-soluble l-cysteine-capped alloyed CdSeS quantum dot passivated with ZnSeTe and ZnSeTe/ZnS shells
- Creator
- Adegoke, Oluwasesan, Nyokong, Tebello, Forbes, Patricia B C
- Date
- 2015
- Type
- Article
- Identifier
- vital:7260
- Identifier
- http://hdl.handle.net/10962/d1020269
- Description
- Alloyed quantum dots (QDs) passivated with shell materials have valuable optical characteristics suitable for a wide array of applications. In this work, alloyed ternary CdSeS QDs passivated with ZnSeTe and ZnSeTe/ZnS shells have been synthesized via a hot-injection method and a ligand exchange reaction employing l-cysteine as a thiol ligand has been used to obtain these water-soluble nanocrystals for the first time. The photoluminescence (PL) quantum yield (QY) of alloyed l-cysteine-capped CdSeS was 71.2% but decreased significantly to 5.2% upon passivation with a ZnSeTe shell. The red shift in PL emission of the CdSeS/ZnSeTe QDs was attributed to be strain-induced whilst a lattice-induced process likely created defect states in the core/shell interface hence contributing to the decline in the PL QY. Nonetheless, the fluorescence stability of CdSeS/ZnSeTe QDs in aqueous solution was unperturbed. Further passivation with a ZnS shell (CdSeS/ZnSeTe/ZnS) improved the PL QY to a value of 58.7% and thus indicates that the defect state in the QDs core/shell/shell structure was reduced. PL lifetime exciton measurements indicated that the rates of decay of the QDs influenced their photophysical properties.
- Description
- Original publication is available at http://dx.doi.org/10.1016/j.optmat.2015.05.024
- Format
- 7 pages, pdf
- Publisher
- Elsevier
- Language
- English
- Relation
- Adegoke, O., Nyokong, T. & Forbes, P. B. C. 2015. Optical properties of water-soluble l-cysteine-capped alloyed CdSeS quantum dot passivated with ZnSeTe and ZnSeTe/ZnS shells. Optical Materials, 46:548–554. Available: http://dx.doi.org/10.1016/j.optmat.2015.05.024.
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Nyokong, Tebello (Distinguished Professor)