Loading...
Please wait, while we are loading the content...
Similar Documents
Photoassisted synthesis of CdSe and core-shell CdSe/CdS quantum dots.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Lin, Yang-Wei Hsieh, Ming-Mu Liu, Ching-Piao Chang, Huan-Tsung |
| Copyright Year | 2005 |
| Abstract | 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. |
| File Format | PDF HTM / HTML |
| DOI | 10.1021/la049489q |
| PubMed reference number | 15641847 |
| Journal | Medline |
| Volume Number | 21 |
| Issue Number | 2 |
| Alternate Webpage(s) | http://ntur.lib.ntu.edu.tw//bitstream/246246/165233/1/54.pdf |
| Journal | Langmuir : the ACS journal of surfaces and colloids |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
