CdS/ZnS Quantum Dots

CdS/ZnS Quantum Dots List

CdS quantum dots is an important nanomaterial, which shows obvious quantum size effect and blue shift of absorption band, and they have great application potential in light emitting diodes, solar cells, nonlinear optical devices and biological markers. However, compared with bulk materials, CdS quantum dots have a very large specific surface area, more defects on the surface, and the optical properties of CdS quantum dots are poor. In order to enhance the luminescence stability, wideband gap semiconductor particle ZnS can be used as the shell to coat narrowband gap semiconductor particle CdS. A core-shell CdS/ZnS quantum dots can be fabricated, and the fluorescence quantum yield is greatly improved. Meanwhile, the cytotoxicity of CdS/ZnS quantum dots can be significantly reduced, which could effectively expand the application in the field of biomedical engineering. As a nanomaterial, the diameter of CdS/ZnS quantum dots is between 1 nm and 10 nm. CdS/ZnS quantum dots can absorb excitation light to produce fluorescence, and the wavelength of fluorescence emission can be adjusted by changing the size of the quantum dots.

Applications:

• Detection field: CdS/ZnS quantum dots are a new kind of fluorescent nanoparticles. Compared with traditional fluorescent dyes, CdS/ZnS quantum dots are characterized by high fluorescence quantum yield, stable luminescence, wide excitation spectrum, narrow emission spectrum and tunable fluorescence, which makes them a promising fluorescent probe. For example, mercury is one of the most toxic heavy metals. Based on the mechanism of fluorescence resonance energy transfer between CdS/ZnS and CdTe quantum dots, a fluorescent probe was designed to detect mercury ions and trace detection can be realized. The addition of mercury ions to the fluorescent probe system can cause fluorescence quenching, and the degree of fluorescence quenching shows a good linear relationship with mercury ions concentration within a certain range.

Figure 1. An example of CdS/ZnS quantum dot applied as a fluorescent probe.

• Solar cell field: As an important method to solve the increasingly serious problem of energy depletion and environmental problems, solar cells have been widely concerned in recent years. Based on CdS/ZnS quantum dots, the designed solar cells have the advantages of low cost, good stability and long life. Moreover, because of the quantum effect, the theoretical efficiency of this type solar cells is very high, which has a promising application prospect.

Figure 2. An example of CdS/ZnS quantum dot applied in solar cell.

• The other: In addition to the mentioned fields, CdS/ZnS quantum dots are also widely used in many fields, such as light-emitting diodes, cell imaging, biosensors and the others.

Classification：

According to the solubility, CdS/ZnS quantum dots can be divided into water-soluble CdS/ZnS quantum dots and non-water-soluble CdS/ZnS quantum dots.

• Water-soluble CdS/ZnS quantum dots: Water-soluble CdS/ZnS quantum dots can be well dissolved in aqueous solution, which are suitable for biological application.
• Non-water-soluble CdS/ZnS quantum dots: The water solubility of this type CdS/ZnS quantum dots is poor, but they have good solubility in oil phase.

References

1. Koneswaran M, Narayanaswamy R. RETRACTED ARTICLE: CdS/ZnS core-shell quantum dots capped with mercaptoacetic acid as fluorescent probes for Hg(II) ions[J]. Microchimica Acta, 2012, 178(1-2).
2. Li Z, Yu L. The Size Effect of TiO2 Hollow Microspheres on Photovoltaic Performance of ZnS/CdS Quantum Dots Sensitized Solar Cell[J]. Materials, 2019, 12(10):1583.