Synthesis Of CdSe/CdS Core/Shell Nanocrystals And Modified Multiwall Carbon Nanotubes

The nano-materials have received considerable attention.because of the unique physics and chemical properties, in which one particularly intriguing case is the study of the structures and properties of nanoscale assembled systems, The unique properties of metal/semiconductor heterostructures at optoelectronic devices, solar energy converters, and photocatalysis make it to be attractive in these fields. Chemical surface modification, doping, and coating can make it possible to modify the physical and chemical properties of CNTs,The functionalization of the surface of CNTs need to be interfaced with a variety of other materials, ranging from inorganic and organic materials. O the other hand, quantum dots are now used extensively for FRET because of their many advantages over fluorescence properties. so the synthesis of the CNT@QDS is very interesting.The thesis mainly includes two parts:1.Under Ar,we synthesized the CdSe nanocrystals in ODE,more we synthesized the CdSe/CdS core-shell nanocrystals under the same reaction regents. And we discussed the influence of the reaction time to the PL properties of the CdSe nanocrystal.And we discussed the influence of the reaction temperature to the PL properties of the CdSe/CdS core-shell nanocrystals .The samples were investigated by TEM, PL. The results indicate that the reaction time play a critical role in the synthesis of the CdSe nanocrystals, the PL peak is red-shifted step by step when ten reaction time enlonged. And the reaction temperature played a critical role for the growth of CdS shell onto CdSe nanocrystals through SILAR in ODE.2. Generally, there are two basic ways to fabricate the heterostructure. The first, CdSe/CdS Core/Shell Nanocrystals are Synthesised after CdSe are anchored onto silica-coated CNTs,The second, CdSe/CdS Core/Shell Nanocrystals are anchored onto silica-coated CNTs after the CdSe/CdS Core/Shell Nanocrystals are synthesized. However, heterostructure that is made according to the first method exhibit large variations in shape and size control in most cases.So later method is choosed. And we discuss that different concentration of QD with the uniform CNT makes the difference of the fluorescence properties. The samples were investigated by TEM, PL. The results indicate that the deposition of a silica shell around the CNTs preserves the fluorescence quenching by insulating the QD from the surface of the CNT. .