近红外发光Ag_2S-CdS核壳结构水溶性量子点的合成及光学性质

Near-Infrared Emitting Ag_2S-CdS Core-Shell Quantum Dots in Aqueous Solution

本文以谷胱甘肽（GSH）作为表面活性剂，采用两步法，先生成Ag2S核，再生长CdS。得到了高质量的Ag2S—CdS核壳结构水溶性量子点。我们用XRD，TEM，HRTEM和EDS研究了产物的结构，形貌和组分，用紫外可见吸收光谱和荧光发射光谱研究了所得量子点的光学性质，同时考察了反应时间，GSH的量，Ag和S源前驱物的含量对量子点光学性质的影响。实验结果表明量子点稳定性好，荧光寿命长，可在710～718nm近红外区域发光。在核生长过程中，Ag和S源的含量同时影响量子点的发光位置和强度，而GSH量和壳层生长中S源的量几乎只影响近红外发光强度，发光位置保持不变。不同的量子点光学性质可能来源于量子点中组分及表面缺陷的分布。

High-quality Ag2S-CdS core-shell water soluble quantum dots have been synthesized via growing CdS shell on the surface of Ag2S core when using glutathione （GSH） as capping agents in aqueous solution. XRD, TEM, HRTEM and EDS were used to characterize the structure, morphology and composition of the samples. The optical properties were studied by UV-Vis absorption and PL. The effects of contents of GSH, Ag and S sources on the optical property have also been studied. The experimental results show that the quantum dots exhibit near- infrared emission in the range of 710-718 nm with long lifetime and high stability. Both the PL peak position and intensity change along with the concentration of Ag and S during the growth of core, while the GSH contents only make the PL peak shift. The different optical properties could be associated with the distribution of Ag and surface states in the core-shell structured quantum dots.