The CuInS2-based quantum dots (QDs) have been showed to have various potential applications including photovoltaic devices, light emitting devices and biomedical imaging. Comparing to Cd-based QDs, which contain carcinogenic cadmium, CuInS2 QDs could have a greater potential in biomedical applications. Another advantage of these QDs is that they show longer fluorescence lifetimes than both molecular probes and Cd-based QDs, which opens up their potential for fluorescence lifetime imaging (FLIM) and time-gated imaging (TGI). However, since CuInS2 QDs are not as well-studied as Cd-based QDs, it is not yet understood which factors are important to optimize these properties. In this work, we show that upon adding ZnS to CuInS2 QDs, the quantum yield increase up to 60% after 12 hours, the emission wavelength is blue-shifted and the particle sizes do not change. These results suggest that there is cation exchange reaction rather than forming a ZnS shell on top of CuInS2 QDs. High resolution TEM (HR-TEM) will be taken to calculate the lattice parameters of the nanocrystals. The energy dispersive X-ray (EDX) and inductively coupled plasma mass spectrometry (ICP-MS) will be used to determine to atomic composition of the QDs. These data can help us to understand the shelling mechanism, such as whether there is a cation exchange process or not. Also, X-ray photoelectron spectroscopy (XPS) will be used to investigate the composition on the surface of the QDs.

Effect of ZnS on structural and optical properties of CuInS2 quantum dots

253rd National Meeting (2017)

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