Applications of CdSe/CdS and CdSe/CdS/ZnS Core/Shell and Core/Shell/Shell nanocrystals are highly dependent on the optical properties. Although, the addition a different shell material on the surface of the core passivates the surface trap states and protects the core from the effect of the environment, it also introduces lattice mismatches at the interface that can also affect the optical properties. To investigate the effects of adding these additional shell materials, we synthesized CdSe/CdS Core/Shell and CdSe/CdS/ZnS Core/Shell/Shell QDs. We have characterized the structural properties of these QDs with high resolution electron microscopy and on-particle elemental analysis, and the optical properties by ensemble and single QDs Spectroscopy. We report the effect of the shell material, thickness and elemental distribution on the quantum yield, fluorescence lifetime and blinking- a phenomenon in which the QDs switches between the bright and dark states under constant illumination. These results will contribute to the understanding of the origin of the trap states that affect excited state decay pathways and blinking in core/shell and core/shell/shell systems and consequently improve the optical properties of these materials.

Effects of elemental distribution and lattice mismatch across CdSe/CdS and CdSe/CdS/ZnS nanocrystals on their optical properties

243rd National Meeting (2012)

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