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首页> 外文期刊>Journal of Materials Chemistry, C. materials for optical and electronic devices >Synthesis and properties of ZnTe and ZnTe/ZnS core/shell semiconductor nanocrystals
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Synthesis and properties of ZnTe and ZnTe/ZnS core/shell semiconductor nanocrystals

机译：ZnTe和ZnTe / ZnS核/壳半导体纳米晶体的合成与性能

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摘要

We report the synthesis of spherical ZnTe nanocrystals and the successive coating with a ZnS shell to afford core/shell quantum dots. These nanocrystals can represent alternatives to cadmium-based quantum dots but their preparation and properties are challenging and relatively unexplored. The effect of various synthetic parameters on the reaction outcome was investigated, and the resulting nanocrystals were characterized by TEM, EDX, XPS, and spectroscopic measurements. The optical data indicate that these core/shell quantum dots belong to type I, i.e., both the electron and the hole are confined within the ZnTe core. Both the ZnTe core and ZnTe/ZnS core/shell quantum dot samples absorb in the visible region and are not luminescent. The ZnS shell preserves the optical properties of the core and improves the chemical and photochemical stability of the nanoparticles in air equilibrated solution, whereas they appear to be quite fragile in the solid state. XPS results have evidenced the distinct nature of core and core/shell QDs, confirming the formation of QDs with shells of different thicknesses and their evolution due to oxidation upon air exposure. Anodic photocurrent generation was observed when an ITO electrode functionalized with ZnTe/ZnS nanocrystals was irradiated in the visible region in a photoelectrochemical cell, indicating that the quantum dots perform spectral sensitization of the electron injection into the ITO electrode. Conversely, cathodic photocurrent generation was not observed; hence, the QD-modified electrode performs electrical rectification under a photon energy input.
机译：我们报告了球形ZnTe纳米晶体的合成以及ZnS壳的连续涂层，以提供核/壳量子点。这些纳米晶体可以代表基于镉的量子点的替代品，但它们的制备和性质具有挑战性，尚未得到充分开发。研究了各种合成参数对反应结果的影响，并通过TEM，EDX，XPS和光谱测量表征了所得的纳米晶体。光学数据表明，这些核/壳量子点属于I型，即电子和空穴都被限制在ZnTe核内。 ZnTe核和ZnTe / ZnS核/壳量子点样品都在可见光区域吸收并且不发光。 ZnS壳保留了核的光学特性，并改善了纳米颗粒在空气平衡溶液中的化学和光化学稳定性，而在固态时它们似乎非常脆弱。 XPS结果证明了核和核/壳QD的独特性质，证实了具有不同厚度的壳的QD的形成以及由于暴露于空气中而氧化的演化。当在光电化学电池中的可见光区域内照射用ZnTe / ZnS纳米晶体功能化的ITO电极时，会观察到阳极光电流的产生，这表明量子点对电子注入ITO电极进行了光谱增感。相反，未观察到阴极光电流的产生。因此，QD修饰电极在光子能量输入下执行电整流。

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