Waterthermal Synthesis Of CdTe And CdTe/CdS Core/Shell Quantum Dots

Quantum dots are zero-dimensional nanomaterials, and their microstructure arisemuch quantum effect, so they have a property, fluorescent property, different frombulk materials. And quantum dots have lots of advantages compared with traditionalfluorescence dyes, such as more fluorescence intensity and longer lifetime, so theyhave been replacing traditional organic fluorescence dyes gradually and became afashionable research subject right now. And they have a sensational applicationforeground in material science, sensor, optics, electronics, and biomedicine. Furthermore, they are so slight that they can be embedded in bodies, so they have extremelygreat value in biomedicine.So far, the preparation method of quantum dots can be generally divided tophysical method and chemical method. Quantum dots can be divided water-solublequantum dots and oil-soluble quantum dots according their solubility. The fluorescentintensity of oil-soluble quantum dots is higher than water-soluble quantum dots. But,compared to oil-soluble quantum dots, water-soluble quantum dots have a great manyvirtues in biologic affinity, and are achieved to apply in biology more easily. Andnow, we research CdS, CdSe, ZnS, ZnSe more frequently.This paper showed the different synthesis method of water-soluble CdTequantum dots and CdTe/CdS core/shell quantum dots. Since the luminescenceproperties of quantum dots will vary with different temperature, pH and reaction time,I demonstrate red-shit of CdTe quantum dots and variety of their fluorescent intensityalong with reaction time and also the dissimilar luminescence effect in the differentpH in the second chapter. In the third chapter, I demonstrate that the change ofluminescence of CdTe quantum dots after coating CdS shell. And then, in the fourthchapter, I used N-acetyl-L-cysteine (NAC) instead of thioglycollic acid (TGA) tosynthesize water-soluble CdTe quantum dots.The emission light of CdTe quantum dots in our experiments is in visible lightregion. TGA is the ligand we used widely to prepare visible-emitting water-solubleCdTe quantum dots at present. Whenas, NAC is the ligand to preparenear-infrared-emitting water-soluble CdTe quantum dots under high temperature andhigh pressure[44]. But I find that we can obtain visible-emitting water-soluble CdTequantum dots under the different reaction conditions. I chose NAC comparing with TGA as ligand to synthesize CdTe quantum dots in the experiment, and thefluorescence of products has been changed obviously.