水相制备CdSe量子点及其ZnS核壳结构量子点

Preparation of CdSe and CdSe/ZnS Core-Shell Quantum Dots in Aqueous Phase

因具有较宽的可调控发光范围,CdSe量子点及其ZnS核壳结构量子点受到了研究者们的普遍关注。采用水相回流法合成了CdSe量子点及其ZnS核壳结构量子点,并结合透射电镜(TEM)、X射线衍射(XRD)、紫外-可见光吸收光谱(UV-Vis)和荧光光谱(PL)对样品进行表征。TEM结果表明,合成的量子点粒径分布较宽且结晶度较高;从XRD分析结果可以看出,CdSe量子点为闪锌矿结构,沿着晶面向外生长ZnS壳层后,谱峰向高角度偏移;从UV-Vis和PL分析结果可以看出,CdSe量子点于500 nm处出现吸收肩峰,于644 nm处出现半高宽较宽的缺陷发光峰;随着反应时间的延长,于577 nm处出现本征发光峰。包覆了ZnS壳层后,量子点不仅发光强度明显增大,而且稳定性显著提高。该合成方法节能环保、生产效率高,具有较大的应用空间。

Due to the wide range of tunable emission peaks, CdSe quantum dots （QDs） and CdSe/ZnS core -shell QDs have attracted many attentions from researchers. Refluxing method was adopted to synthesize CdSe QDs and CdSe/ZnS core -shell QDs, and transmission electron microscopy （TEM）, X- ray diffraction （XRD）, UV- Vis absorption spectroscopy （UV- Vis） and photoluminescence spectra （PL） were used for characterization in this paper. The TEM images show that the size distribution of QDs is wide and the crystallinity is high. From the XRD spectra, it can be found that CdSe QDs pos- sess zinc - blende structure, and the peak shifts to higher angle when ZnS shells are grown along the crystal plane by epitaxi- al growth method. From the UV - Vis and PL spectra of CdSe QDs, an absorption peak and a defect emission peak with large half width can be detected at 500 nm and 644 nm, respectively. With the refluxing time increasing, an intrinsic emission peak occurred at 577 nm. The ZnS outer layer can not only increase the luminescence intensity of CdSe QDs, but also further improve the stability. This synthesis method saves energy, possesses high production efficiency, friendly environmental protection, which has a larger application area.