| Recently, colloidal luminescent semiconductor nanocrystals are of great interest for both fundamental research and technical applications, due to their unique properties. Colloidal luminescent semiconductor nanocrystals have several inherent functional advantages compared to organic dyes. The photoluminescence (PL) emissions of high-quality semiconductor nanocrystals are narrow, symmetric, and strongly size-dependent. The absorption spectra of nanocrystals with different sizes all extend from the onset to deep UV. These spectral features make it possible to carry out multiple labeling with a single-laser setup. Core/shell nanocrystals formed by growing a lattice-matched, higher band gap material on the top of the core are quite stable against photo-oxidation. With the recent developments in synthetic chemistry, nearly monodisperse, highly luminescent semiconductor plain core and core/shell nanocrystals covering an entire optical window could be prepared at low cost with so-called greener approaches. All those features have attracted tremendous interest in exploring novel materials based on semiconductor nanocrystals.CdTe was chosen because it was a representative example of the important luminescent semiconductor nanocrystals that has been used in numerous applications, such as in light-emitting devices, photoelectrochemical cells, photonic and biological labels. My dissertation is focused on the preparation, assembly,composite and primary application of luminescent CdTe nanocrystals. Now many novel results are obtained from our experiments. The main results are outlined as followings.(1) Preparation of CdTe quantum dots (QDs), nanowires and nanorods. Control of luminescent properties and shape of nanocrystals has been playinga critical role in this very active field. The thioglycolic acid (TGA)-capped CdTe QDs were prepared using the reaction between Cd(ClO4)2 6H2O and NaHTe in aqueous solution. The effects on luminescent properties of CdTe QDs were studied under a serial of reaction conditions, such as the change of pH value, the amount of TGA added, the ratio of reaction precursor (Cd2+ to Te2") in detail. The relative optimal conditions were found for synthesis of different sized CdTe QDs.The CdTe QDs prepared as above were spontaneously organized into luminescent CdTe nanowires. One of the key steps in the preparation of nanowires from nanoparticles was the partial removal of stabilizer. The permanent dipole moment of CdTe is the driving force.Based on this result, the dipole moment of semiconductor and the chelate function between the amino acid ligands and ions of transition elements were utilized in the strategy for achieving CdTe nanorods. To the best of our knowledge, this is the first report of synthesis of highly luminescent water-soluble CdTe nanorods. HREM image has shown that the (200) plane of cubic crystal lattice was the predominant growth orientation. The aspect ratio and the PL peak of CdTe nanorods could be easily controlled by the refluxing time.(2) Fabrication of unique structure and photoluminescence of Au/CdTe nanostructure materialsNow building and patterning of semiconductors nanocrystals into two- and three- dimensional organized and designed structures is an important goal in materials chemistry for the application of the ordered system in electronic, sensor, and photonic devices. CdTe QDs were self-organized into spherical aggregates using Au as seeds. The formation mechanism is considered to be a cooperative effect of dipole-dipole interaction and the nanocrystals growth in the given reaction environment. "Abnormal" red shift of the photoluminescence peak of the spherical aggregates was observed. The unique structure is related to their "abnormal" photoluminescence. In the spherical aggregates, the distance between each CdTenanocrystals is very small, and there is strong dipole-dipole interaction between the CdTe nanocrystals, which leads to the formation of so-called exciton states, which are delocalized over several CdTe nanocrystals.(3) Incorporation of lum...
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