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| 題名: | Photo-assisted Synthesis of CdSe and Core-Shell CdSe/CdS Quantum Dots |
| 作者: | Lin, Y.-W.;Hsieh, M.-M.;Liu, C.-P.;Chang, H.-T. |
| 貢獻者: | 化學系 |
| 日期: | 2005
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| 上傳時間: | 2010-11-10T06:32:49Z
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| 摘要: | 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 °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 °C) byCdSusing thioacetamide as theSsource (Se:S concentration
ratio of 1) at 80 °C for 24 h, the quantum yield of the core-shell CdSe/CdS QDs at 603 nm is 2.4%. Under UVirradiation 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. |
| 關聯: | Langmuir, 21, 728-734 |
| 顯示於類別: | [化學系] 期刊論文
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