Alloyed Quantum Dots

Alloyed Quantum Dots List

Quantum dots are excellent nanomaterials with the unique physical and chemical properties. Quantum dots have broad application prospects in biomedical, photoelectric devices and other fields, which has attracted the attention of the vast number of scientific workers. In the early stage of quantum dots research, many researches are done on binary quantum dots, and the emission wavelength regulation of quantum dots is mainly based on the quantum size effect of quantum dots. However, the limitation of this method is gradually discovered in the application. Taking CdSe quantum dots as an example, it is difficult to obtain small size or large size quantum dots by adjusting the synthesis conditions, which leads to the difficulty in synthesis of CdSe quantum dots with blue fluorescence and near-infrared fluorescence. In order to solve these problems, alloyed quantum dots are developed. Alloyed quantum dots are constituted by multiple components, and the band gap width of the quantum dots can be adjusted by changing the component ratio of each element. Therefore, the particle size and emission wavelength of the quantum dots no longer show a linear relationship, and different physical and chemical properties can be obtained.

Applications:

• Light-emitting diode field: Alloyed quantum dots have the advantages of wide absorption, narrow emission and high color purity, which is a kind of ideal light-emitting material and widely used in the field of light-emitting diode. Based on the alloyed quantum dots, the red, green and blue QLEDs devices can be constructed. The devices have high luminous efficiency and low working voltage, and the corresponding wide color range values can restore the real colors to the maximum extent.
• Biochemical sensor: When adding the alloyed quantum dots in solution, their fluorescence intensity is affected by the molecules or ions in the surrounding solution. Using this characteristic, biochemical sensors can be designed. In addition, after certain surface modification, alloyed quantum dots can be applied in organisms or biological blood to achieve sensitive detection of specific ions or biological macromolecules.

Figure 1. An example of alloyed quantum dots applied as biochemical sensor.

• Bioluminescence labeling and imaging field: The size of the alloyed quantum dots is small and they can enter the cell by phagocytosis. Moreover, the alloyed quantum dots have low cytotoxicity and do not affect the normal metabolism of organisms, which can be used as a fluorescent probe for cell labeling and imaging. Due to the excellent biocompatibility of the alloyed quantum dots, specific biological macromolecules such as polypeptides, proteins and antibodies can be modified on the surface of the quantum dots, and targeted recognition of cancer cells can be realized, which has broad application prospects in disease diagnosis and treatment.

Figure 2. An example of alloyed quantum dots applied in bioluminescence imaging field.

Classification:

According to the components, alloyed quantum dots can be divided into ternary alloyed quantum dots, quaternary alloyed quantum dots and the others. Among them, ternary alloyed quantum dots are the mostly studied, including CdSeS, CdSeTe, ZnCdSe, CdHgTe, CuInS, CuInSe and the others.

References

1. Liu S, Li Y, Su X. Determination of copper(II) and cadmium(II) based on ternary CuInS₂ quantum dots[J]. Analytical Methods, 2012, 4(5):1365-1370.
2. Anila Arshad, Hongli Chen, Xilin Bai, et.al. One-Pot Aqueous Synthesis of Highly Biocompatible Near Infrared CuInS₂ Quantum Dots for Target Cell Imaging[J]. Chinese Journal of Chemistry, 2016.