Fabrication And Characterization Of Core/Shell Quantum Dots And Composite Films

As a kind of inorganic emitter with distinct optical properties, quantum dots have received renewed attention in optical and biomedical fields. Different color-emitting QDs(semiconductor nanocrystals) can be prepared with different sizes. They also can be fabricated through the control of constituent stoichiometry in alloy nanoparticles. When these nanoparticles are embedded in a polymer matrix, highly transparent composites to serve as prototype luminescent solar concentration applications can be obtained which have significant potential. In addition, after surface modification the high quality hydrophobic QDs turn into hydrophilic.A new Se precursor is used to synthesis CdSe through phosphine-free method. But the optical efficiency is low. When it is made into core/shell structure, the quantum yield can improve substantially under passivation and barrier function. Then the chemical composition is changed. A series of high quality alloy nanocrystals have different band gap, which means the energy of light. In macro-scale it leads to different color. The core/shell structure is also used to boost the quantum optical efficiency and stability of the alloy materials.Low reabsorption(minimal spectral overlap between the emission and absorption spectra) and high fluorescence quantum efficiency are two key properties for the appropriate materials in luminescent solar concentrators. Mn:ZnS quantum dots are embedded in a polymer matrix, yielding highly transparent composites. This prototype has received great expectation.Last but not the least, this paper draws attention in the water-soluble QDs. Though hydrophobic nanoparticles have high efficiency, the water solubility is a big flaw in the biomedical application. The immediate surface modification can turn QDs into hydrophilic, but with a low efficiency. QDs are modificated by alkylthiol and then by mercaptopropionic acid. The efficiency can reach 25%.