| Photoassisted synthesis of CdSe and core-shell CdSe/CdS quantum dots. | |
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MedLine Citation:
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PMID: 15641847 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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This paper describes the synthesis of core-shell CdSe/CdS quantum dots (QDs) in aqueous solution by a simple photoassisted method. CdSe was prepared from cadmium nitrate and 1,1-dimethylselenourea precursors under illumination for up to 3 h using a pulsed Nd:YAG laser at 532 nm. The effects that the temperature and the laser irradiation process have on the synthesis of CdSe were monitored by a series of experiments using the precursors at a Cd:Se concentration ratio of 4. Upon increasing the temperature (80-140 degrees C), the size of the CdSe QDs increases and the time required for reaching a maximum photoluminescence (PL) is shortened. Although the as-prepared CdSe QDs possess greater quantum yields (up to 0.072%) compared to those obtained by microwave heating (0.016%), they still fluoresce only weakly. After passivation of CdSe (prepared at 80 degrees C) by CdS using thioacetamide as the S source (Se:S concentration ratio of 1) at 80 degrees C for 24 h, the quantum yield of the core-shell CdSe/CdS QDs at 603 nm is 2.4%. Under UV irradiation of CdSe/CdS for 24 h using a 100-W Hg-Xe lamp, the maximum quantum yield of the stable QDs is 60% at 589 nm. A small bandwidth (W1/2 < 35 nm) indicates the narrow size distribution of the as-prepared core-shell CdSe/CdS QDs. This simple photoassisted method also allows the preparation of differently sized (3.7-6.3-nm diameters) core-shell CdSe/CdS QDs that emit in a wide range (from green to red) when excited at 480 nm. |
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Authors:
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Yang-Wei Lin; Ming-Mu Hsieh; Ching-Piao Liu; Huan-Tsung Chang |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Langmuir : the ACS journal of surfaces and colloids Volume: 21 ISSN: 0743-7463 ISO Abbreviation: Langmuir Publication Date: 2005 Jan |
Date Detail:
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Created Date: 2005-01-11 Completed Date: 2006-07-28 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9882736 Medline TA: Langmuir Country: United States |
Other Details:
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Languages: eng Pagination: 728-34 Citation Subset: - |
Affiliation:
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Department of Chemistry, National Taiwan University, Section 4, Roosevelt Road, Taipei, Taiwan. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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