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首页> 外文期刊>Nanotechnology >Self-assembly of ZnS-encapsulated SiO2 nanospheres for enhanced photoluminescence
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Self-assembly of ZnS-encapsulated SiO2 nanospheres for enhanced photoluminescence

机译：ZnS包裹的SiO2纳米球的自组装，可增强光致发光

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摘要

ZnS-encapsulated spherical SiO2 nanostructures were prepared by a one-step solvothermal method. The samples were characterized by x-ray diffraction, transmission electron microscopy, selected-area electron diffraction, infrared spectra, UV-visible spectra, and photoluminescence. It is found that 27 nm ZnS in a wurtzite phase was encapsulated by a low-porosity SiO2 layer, which compares to a particle size of 8.5 nm for bare ZnS as prepared under similar conditions. Contrary to the theoretical predictions of the quantum size effect, the encapsulated ZnS showed a band gap energy surprisingly larger than that for the bare one. Moreover, the encapsulated ZnS/ SiO2 nanostructures exhibited 'self-activated centers', as characterized by a blue photoluminescence emission band at 430 nm, while the bare ZnS nanoparticles gave a surface sulfur species-mediated green emission at 520 nm. These observations are explained in terms of the encapsulated nanostructure and the relevant defect nature in which the SiO2 layer reduces the nonradiative recombination centers and enhances the photoluminescence intensity.
机译：通过一步溶剂热法制备了ZnS封装的球形SiO2纳米结构。通过X射线衍射，透射电子显微镜，选择区域电子衍射，红外光谱，UV-可见光谱和光致发光来表征样品。发现纤锌矿相中的27 nm ZnS被低孔隙度SiO2层包裹，相比之下，在相似条件下制备的裸露ZnS的粒径为8.5 nm。与量子尺寸效应的理论预测相反，封装的ZnS显示出的带隙能量惊人地大于裸露的带隙能量。此外，封装的ZnS / SiO2纳米结构表现出“自活化中心”，其特征是在430 nm处有蓝色光致发光发射带，而裸露的ZnS纳米颗粒在520 nm处具有表面硫物种介导的绿色发射。这些观察是根据包封的纳米结构和相关的缺陷性质来解释的，其中SiO 2层减少了非辐射复合中心并增强了光致发光强度。

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