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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

Results of UV illumination treatment of the as-prepared CdTe/CdSe core/shell QDs. PL spectra of CdTe/CdSe QDs after UV treatment, which indicates that the PL intensity of the CdTe/CdSe QDs could be enhanced by the lasting time of UV illumination. The PL intensities of the as-prepared CdTe/CdSe QDs were recorded at the same absorbance values at the first excitation the absorption peak.
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Figure 4: Results of UV illumination treatment of the as-prepared CdTe/CdSe core/shell QDs. PL spectra of CdTe/CdSe QDs after UV treatment, which indicates that the PL intensity of the CdTe/CdSe QDs could be enhanced by the lasting time of UV illumination. The PL intensities of the as-prepared CdTe/CdSe QDs were recorded at the same absorbance values at the first excitation the absorption peak.

Mentions: We also perform the UV-illuminated treatment for improving the PLQY of our as-received CdTe/CdSe QDs. In our case, we found that the adding of 3-MPA to the as-prepared CdTe/CdSe QD solution caused a decrease of the PL intensity. To avoid this kind of fluorescence quenching but still provide S2- for illumination, we made a solution including Cd2+ and MPA (molar ratio [Cd2+]/[MPA] = 1:2.4) instead of pure MPA molecule, and the PH value of the solution was adjusted to 11.2. The as-prepared CdTe/CdSe QDs were diluted to the same concentration with the corresponding CdTe QDs and illuminated treatment with UV lamps, and the results are shown in Figure 4. It was found that the PL intensity of the as-prepared CdTe/CdSe QDs was greatly enhanced during illumination. After 65 min of illumination, the PL intensity of CdTe/CdSe achieved at the highest level with the PLQY of 45%. The UV illumination provides a novel photochemical treatment approach for the enhancement of the PLQY of the QDs. Similar results have been reported elsewhere, such as the photoetching of thiol-capped CdTe [22] and the photochemical treatment of ZnSe nanocrystals [23].


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

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

Results of UV illumination treatment of the as-prepared CdTe/CdSe core/shell QDs. PL spectra of CdTe/CdSe QDs after UV treatment, which indicates that the PL intensity of the CdTe/CdSe QDs could be enhanced by the lasting time of UV illumination. The PL intensities of the as-prepared CdTe/CdSe QDs were recorded at the same absorbance values at the first excitation the absorption peak.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211493&req=5

Figure 4: Results of UV illumination treatment of the as-prepared CdTe/CdSe core/shell QDs. PL spectra of CdTe/CdSe QDs after UV treatment, which indicates that the PL intensity of the CdTe/CdSe QDs could be enhanced by the lasting time of UV illumination. The PL intensities of the as-prepared CdTe/CdSe QDs were recorded at the same absorbance values at the first excitation the absorption peak.
Mentions: We also perform the UV-illuminated treatment for improving the PLQY of our as-received CdTe/CdSe QDs. In our case, we found that the adding of 3-MPA to the as-prepared CdTe/CdSe QD solution caused a decrease of the PL intensity. To avoid this kind of fluorescence quenching but still provide S2- for illumination, we made a solution including Cd2+ and MPA (molar ratio [Cd2+]/[MPA] = 1:2.4) instead of pure MPA molecule, and the PH value of the solution was adjusted to 11.2. The as-prepared CdTe/CdSe QDs were diluted to the same concentration with the corresponding CdTe QDs and illuminated treatment with UV lamps, and the results are shown in Figure 4. It was found that the PL intensity of the as-prepared CdTe/CdSe QDs was greatly enhanced during illumination. After 65 min of illumination, the PL intensity of CdTe/CdSe achieved at the highest level with the PLQY of 45%. The UV illumination provides a novel photochemical treatment approach for the enhancement of the PLQY of the QDs. Similar results have been reported elsewhere, such as the photoetching of thiol-capped CdTe [22] and the photochemical treatment of ZnSe nanocrystals [23].

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