Selective synthesis and advanced characteristic of CdSe semiconductor quantum dots by aqueous phase

Abstract

This work mainly investigated the influences of some factors, such as, synthesis methods, precursor alternatives, and vacuum heat-treating process, etc, on the fluorescent characteristics of the semiconductor quantum dots synthesized by aqueous phase. The research results indicate that the fluorescent characteristic of water-solution sample prepared from Na₂ S0₃ precursor was sensitive to water bath heating time, and specially, its photoluminescence spectrum shows the unique phenomenon of double excitation and emission peaks. Meanwhile, the fluorescent characteristic of water-solution sample prepared from NaBH₄ precursor is slightly influenced by water bath heating time, and the surface of CdSe quantum dots could be passivated by the excessive amount of NaBH₄ precursor, which results in the effective decrease of surface traps and great enhancement of quantum yield. Furthermore, the fluorescent emission peaks of samples could be sharpened by vacuum heat-treating process, with its spectral full width at half of maximum (FWHM) around 30–40 nm, so the emission peaks become redshifi, of which the intensity greatly increases.

Keywords

semiconductor quantum dots / CdSe / synthesis by aqueous phase / fluorescence

References

[1] Sathyajith Ravindran, Sumit Chaudhary, Brooke Colburn, Mihrimach Ozkan, Cengiz S Ozkan. Covalent Coupling of Quantum Dots to Multiwalled Carbon Nanotubes for Electronic Device Applications.Nano Letters, 2003, (4): 447–452

[2] Ravindran Sathyajith, Sunran Kim, Rebecca Martin, Lord Elizabeth M, Ozkan Cengiz S. Quantum Dots as Bio-labels for the Localization of a Small Plant Adhesion Protein. Nanotechnology, 2005, 16(1): 1-4.

[3] Goldman Ellen R, Clapp Aaron R, Anderson George P, Uyeda H Tetsuo, Mauro J Matthew, Medintz Igor L, Mattoussi Hedi. Multiplexed Toxin Analysis Using Four Colors of Quantum dots Fluoroeagents. Anal. Chem., 2004, 76(3): 684-688.

[4] Dabbousi B O, Rodriguez-Viejo J, Mikulec F V, Heine J R, Mattoussi H, Ober R, Jensen K F, Bawendi M G. (CdSe) ZnS Core-Shell Quantum Dots: Synthesis and Characterization of a Size Series of Highly Luminescent Nanocrystallites. J. Phys. Chem. B, 1997, 101(46): 9463-9475.

[5] Bailey Robert E, Smith Andrew M, Nie Shuming. Low-Dimensional Systems and Nanostructures. Physica E, 2004, 25(1): 1-12.

[6] Kim Joong Hyun, Morikis Dimitrios, Ozkan Mihrimah. Adaptation of Inorganic Quantum Dots for Stable Molecular Beacons. Sensors and Actuators B, 2004, 102(12): 315-319.

[7] Woggon U. Optical Properties of Semiconductor Quantum Dots, 1997 Berlin: Springer.

[8] Ying Xie, Jing-juan Xu, Jun-sheng Yu, Hong-yuan Cheng. Synthesis and Characterization of Water-soluble CdSe/ZnS Core-shell Nanoparticles. Chinese Journal of Inorganic Chemistry, 2004, 20(6): 663-667.

[9] Kayanuma Y. Quantum-size Effects of Interacting Electrons and Holes in Semiconductor Microcrystals with Spherical Shape. Phys Rev B, 1998, 38: 9797-9805.

[10] Chang-Xu ShI, Heng-De Li, Lian Zhou. Handbook of Materials Science and Engineering, 2004 Beijing: Chemical Industry Press.

[11] Jang Eunjoo, Jun Shinae, Chung Youngsu, Pu Lyongsun. Surface Treatment to Enhance the Quantum Efficiency of Semiconductor Nanocrystals. J. Phys. Chem. B, 2004, 108(15): 4597-4600.