Xie Cong, Zhao Yubin, Song Yuxiang, Liu Yingjie, Wang Yaya, Yang Ping
School of Material Science and Engineering, University of Jinan, Jinan, 250022, P. R. China.
J Nanosci Nanotechnol. 2020 Sep 1;20(9):5478-5485. doi: 10.1166/jnn.2020.17877.
Compared with conventional semiconductor quantum dots, hybrid SiO₂ coated CdTe QDs exhibited high stability, long fluorescent lifetime, high photoluminescence quantum yields, and well biocompatibility. In this paper, CdTe QDs with tunable PL from green to red emitting were prepared by an aqueous synthesis. A sol-gel process resulted in CdTe QDs coated with a hybrid SiO₂ shell contained CdS-like clusters to obtain red-shifted PL spectra, increased PL efficiency and high stability. The clusters were formed by the reaction of Cd and S ions generated via the decomposition of thioglycolic acid. The clusters around CdTe cores created a core-shell structure which is very similar with traditional semiconductor core-shell QDs. After being coated with a hybrid SiO₂ shell, the PL of green-emitting naked CdTe QDs was red-shifted largely (30 nm) while the PL of yellowemitting CdTe QDs revealed a small red-shifted (20 nm). Furthermore, The PL of red-emitting naked CdTe QDs was red-shifted much small (less than 10 nm). This phenomenon is ascribed to the change of band gap of CdTe cores with sizes. The red-shift of PL spectra is attributed to the CdS-like clusters around the core rather than the thickness of the hybrid SiO₂ shell.
与传统半导体量子点相比，杂化二氧化硅包覆的碲化镉量子点表现出高稳定性、长荧光寿命、高光致发光量子产率以及良好的生物相容性。本文采用水相合成法制备了具有从绿色到红色发射的可调谐光致发光的碲化镉量子点。溶胶 - 凝胶法使碲化镉量子点包覆了含有类硫化镉簇的杂化二氧化硅壳层，从而获得红移的光致发光光谱、提高的光致发光效率和高稳定性。这些簇是由巯基乙酸分解产生的镉离子和硫离子反应形成的。碲化镉核周围的簇形成了一种与传统半导体核壳量子点非常相似的核壳结构。在包覆杂化二氧化硅壳层后，绿色发射的裸碲化镉量子点的光致发光发生了很大的红移（约30 nm），而黄色发射的碲化镉量子点的光致发光则显示出较小的红移（约20 nm）。此外，红色发射的裸碲化镉量子点的光致发光红移很小（小于10 nm）。这种现象归因于碲化镉核的带隙随尺寸的变化。光致发光光谱的红移归因于核周围的类硫化镉簇，而不是杂化二氧化硅壳层的厚度。
