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Microwave-assisted synthesis of water-dispersed CdTe/CdSe core/shell type II quantum dots.

Sai LM, Kong XY - Nanoscale Res Lett (2011)

Bottom Line: A facile synthesis of mercaptanacid-capped CdTe/CdSe (core/shell) type II quantum dots in aqueous solution by means of a microwave-assisted approach is reported.The results of X-ray diffraction and high-resolution transmission electron microscopy revealed that the as-prepared CdTe/CdSe quantum dots had a core/shell structure with high crystallinity.The photoluminescent properties were dramatically improved through UV-illuminated treatment, and the time-resolved fluorescence spectra showed that there is a gradual increase of decay lifetime with the thickness of CdSe shell.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Material Science and Engineering, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240, People's Republic of China. xykong@sjtu.edu.cn.

ABSTRACT
A facile synthesis of mercaptanacid-capped CdTe/CdSe (core/shell) type II quantum dots in aqueous solution by means of a microwave-assisted approach is reported. The results of X-ray diffraction and high-resolution transmission electron microscopy revealed that the as-prepared CdTe/CdSe quantum dots had a core/shell structure with high crystallinity. The core/shell quantum dots exhibit tunable fluorescence emissions by controlling the thickness of the CdSe shell. The photoluminescent properties were dramatically improved through UV-illuminated treatment, and the time-resolved fluorescence spectra showed that there is a gradual increase of decay lifetime with the thickness of CdSe shell.

No MeSH data available.


Related in: MedlinePlus

Band structure alignment. (a) Alignment of the conduction and valence band edges for CdTe/CdSe core/shell type II heterostructures. (b) XRD patterns of CdTe and CdTe/CdSe core/shell QDs via microwave-assisted synthesis. The black bars at the bottom represent the XRD pattern of bulk CdTe (cubic). The black bars at the top represent the XRD pattern of bulk CdSe (cubic). (c) TEM bright field image of the CdTe core QDs in low magnification, the inset for the HRTEM image of CdTe QD with cubic structure. (d) HRTEM image of CdTe/CdSe core/shell QD, different contrasts corresponding to the CdTe core and CdSe shell, respectively. The thickness of the shell is about four to five atomic layers.
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Figure 1: Band structure alignment. (a) Alignment of the conduction and valence band edges for CdTe/CdSe core/shell type II heterostructures. (b) XRD patterns of CdTe and CdTe/CdSe core/shell QDs via microwave-assisted synthesis. The black bars at the bottom represent the XRD pattern of bulk CdTe (cubic). The black bars at the top represent the XRD pattern of bulk CdSe (cubic). (c) TEM bright field image of the CdTe core QDs in low magnification, the inset for the HRTEM image of CdTe QD with cubic structure. (d) HRTEM image of CdTe/CdSe core/shell QD, different contrasts corresponding to the CdTe core and CdSe shell, respectively. The thickness of the shell is about four to five atomic layers.

Mentions: The typical band structure alignment of the conduction and valence band edges for the CdTe/CdSe core/shell type II heterostructures is shown in Figure 1a. With regard to the core/shell structures, the separation of the hole and the electron can be achieved upon excitation. The hole is mostly confined in the CdTe core while the electron is in the CdSe shell. The as-received CdTe and CdTe/CdSe core/shell QDs via microwave-assisted synthesis were examined systematically from the crystallography structure to the unique optical properties.


Microwave-assisted synthesis of water-dispersed CdTe/CdSe core/shell type II quantum dots.

Sai LM, Kong XY - Nanoscale Res Lett (2011)

Band structure alignment. (a) Alignment of the conduction and valence band edges for CdTe/CdSe core/shell type II heterostructures. (b) XRD patterns of CdTe and CdTe/CdSe core/shell QDs via microwave-assisted synthesis. The black bars at the bottom represent the XRD pattern of bulk CdTe (cubic). The black bars at the top represent the XRD pattern of bulk CdSe (cubic). (c) TEM bright field image of the CdTe core QDs in low magnification, the inset for the HRTEM image of CdTe QD with cubic structure. (d) HRTEM image of CdTe/CdSe core/shell QD, different contrasts corresponding to the CdTe core and CdSe shell, respectively. The thickness of the shell is about four to five atomic layers.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3211493&req=5

Figure 1: Band structure alignment. (a) Alignment of the conduction and valence band edges for CdTe/CdSe core/shell type II heterostructures. (b) XRD patterns of CdTe and CdTe/CdSe core/shell QDs via microwave-assisted synthesis. The black bars at the bottom represent the XRD pattern of bulk CdTe (cubic). The black bars at the top represent the XRD pattern of bulk CdSe (cubic). (c) TEM bright field image of the CdTe core QDs in low magnification, the inset for the HRTEM image of CdTe QD with cubic structure. (d) HRTEM image of CdTe/CdSe core/shell QD, different contrasts corresponding to the CdTe core and CdSe shell, respectively. The thickness of the shell is about four to five atomic layers.
Mentions: The typical band structure alignment of the conduction and valence band edges for the CdTe/CdSe core/shell type II heterostructures is shown in Figure 1a. With regard to the core/shell structures, the separation of the hole and the electron can be achieved upon excitation. The hole is mostly confined in the CdTe core while the electron is in the CdSe shell. The as-received CdTe and CdTe/CdSe core/shell QDs via microwave-assisted synthesis were examined systematically from the crystallography structure to the unique optical properties.

Bottom Line: A facile synthesis of mercaptanacid-capped CdTe/CdSe (core/shell) type II quantum dots in aqueous solution by means of a microwave-assisted approach is reported.The results of X-ray diffraction and high-resolution transmission electron microscopy revealed that the as-prepared CdTe/CdSe quantum dots had a core/shell structure with high crystallinity.The photoluminescent properties were dramatically improved through UV-illuminated treatment, and the time-resolved fluorescence spectra showed that there is a gradual increase of decay lifetime with the thickness of CdSe shell.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Material Science and Engineering, Shanghai Jiao Tong University, Dongchuan Road 800, Shanghai 200240, People's Republic of China. xykong@sjtu.edu.cn.

ABSTRACT
A facile synthesis of mercaptanacid-capped CdTe/CdSe (core/shell) type II quantum dots in aqueous solution by means of a microwave-assisted approach is reported. The results of X-ray diffraction and high-resolution transmission electron microscopy revealed that the as-prepared CdTe/CdSe quantum dots had a core/shell structure with high crystallinity. The core/shell quantum dots exhibit tunable fluorescence emissions by controlling the thickness of the CdSe shell. The photoluminescent properties were dramatically improved through UV-illuminated treatment, and the time-resolved fluorescence spectra showed that there is a gradual increase of decay lifetime with the thickness of CdSe shell.

No MeSH data available.


Related in: MedlinePlus