Influence of acid on luminescence properties of thioglycolic acid-capped CdTe quantum dots
Influence of acid on luminescence properties of thioglycolic acid-capped CdTe quantum dots
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DOI：
10.1021/jp801043e
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发表时间：
2008-06-05
影响因子：
3.7
通讯作者：
Tamai, Naoto
中科院分区：
文献类型：
--
作者：
Mandal, Abhijit;Tamai, Naoto
以巯基乙酸（TGA）为稳定剂，在水溶液中通过Cd2+与H2Te反应制备了CdTe量子点。为了提高量子产率（QY），我们系统地优化了合成条件，发现pH值对CdTe量子点的光学性质有显著影响。在合成不同尺寸的CdTe量子点后，我们扩展了我们的观察，以检查pH值对不同尺寸的CdTe量子点的影响。实验结果表明。当溶液酸性达到一定的pH值时，TGA覆盖的CdTe量子点的发光QY以及寿命显著增加。这种观察在较小尺寸的QD的情况下更加明显。光谱研究表明，CdTe量子点发光的pH依赖性是由量子点表面的结构变化引起的，而不是量子点的大小。在低pH下观察到的浊度表明形成了QD的聚集体。稳态光谱和原子力显微镜研究证实了这一点。我们观察到，当溶液的pH值恢复到其初始值时，发光强度和吸光度的变化都是可逆的。
CdTe quantum dots (QDs) were prepared in aqueous solution by the reaction between Cd2+ and H2Te in the presence of thioglycolic acid (TGA) as a stabilizer. In order to improve the quantum yield (QY), we systematically optimized the synthesis conditions and found that the pH value significantly affected the optical properties of CdTe QDs. After synthesizing different sizes of CdTe QDs, we have extended our observation to check the effect of pH level on different sizes of CdTe QDs. Experimental results reveal that. the luminescence QY as well as the lifetime of TGA-capped CdTe QDs increased noticeably when the solution was made acidic up to a certain pH level. This observation is much more pronounced in the case of smaller size QDs. The optical spectroscopy studies imply that the pH-dependent behavior of the luminescence of CdTe QDs is caused by structural changes on the surface rather than the size of the QDs. Turbidity observed at low pH indicates the formation of aggregates of QDs. This is confirmed by steady-state spectroscopy and atomic force microscopy studies. We observed that both the luminescence intensity and absorbance changes were reversible when the pH level of the solution was brought back its original value.