School of Chemical and Physical Sciences and the MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington , Wellington 6012, New Zealand.
Acc Chem Res. 2014 Oct 21;47(10):3045-51. doi: 10.1021/ar500215v. Epub 2014 Sep 25.
Understanding and unlocking the potential of semiconductor nanocrystals (NCs) is important for future applications ranging from biomedical imaging contrast agents to the next generation of solar cells and LEDs. Silicon NCs (Si NCs) have key advantages compared with other semiconductor NCs due to silicon's high natural abundance, low toxicity and strong biocompatibility, and unique size, and surface dependent optical properties. In this Account, we review and discuss the synthesis, surface modification, purification, optical properties, and applications of Si NCs. The synthetic methods used to make Si NCs have improved considerably in the last 5-10 years; highly monodisperse Si NCs can now be produced on the near gram scale. Scaled-up syntheses have allowed scientists to drive further toward the commercial utilization of Si NCs. The synthesis of doped Si NCs, through addition of a simple elemental precursor to a reaction mixture or by the production of a single source precursor, has shown great promise. Doped Si NCs have demonstrated unique or enhanced properties compared with pure Si NCs, for example, magnetism due to the presence of magnetic metals like Fe and Mn. Surface reactions have reached a new level of sophistication where organic (epoxidation and diol formation) and click (thiol based) chemical reactions can be carried out on attached surface molecules. This has led to a wide range of biocompatible functional groups as well as a degree of emission tuneability. The purification of Si NCs has been improved through the use of size separation columns and size selective precipitation. These purification approaches have yielded highly monodisperse and pure Si NCs previously unachieved. This has allowed scientists to study the size and surface dependent properties and toxicity and enabled the use of Si NCs in biomedical applications. The optical properties of Si NCs are complex. Using a combination of characterization techniques, researchers have explored the relation between the optical properties and the size, surface functionalization, and preparation method. This work has led to a greater fundamental understanding of the unique optical properties of Si NCs. Si NCs are being studied for a wide range of important applications, including LEDS with tunable electroluminescence ranging from NIR to yellow, the encapsulation of Si NCs within micelles terminated with proteins to allow targeted in vivo imaging of cells, Si NC-polymer hybrid solar cells, and the use of Si NCs in battery anodes with high theoretical capacity and good charge retention.
理解和挖掘半导体纳米晶体（NCs）的潜力对于从生物医学成像对比剂到下一代太阳能电池和发光二极管的未来应用都非常重要。与其他半导体 NCs 相比，硅 NCs（Si NCs）具有关键优势，因为硅具有高的天然丰度、低毒性和强生物相容性，以及独特的尺寸和表面依赖性光学性质。在本报告中，我们回顾和讨论了 Si NCs 的合成、表面修饰、纯化、光学性质和应用。在过去的 5-10 年中，用于制备 Si NCs 的合成方法有了很大的改进；现在可以在近克级规模上制备高度单分散的 Si NCs。规模化合成使科学家们进一步推动 Si NCs 的商业化利用。通过在反应混合物中添加简单的元素前体或通过制备单源前体，合成掺杂 Si NCs 具有很大的前景。与纯 Si NCs 相比，掺杂 Si NCs 具有独特或增强的性质，例如由于存在铁和锰等磁性金属而具有磁性。表面反应达到了新的复杂程度，其中可以在附着的表面分子上进行有机（环氧化和二醇形成）和点击（基于硫醇）化学反应。这导致了广泛的生物相容性官能团以及一定程度的发射可调谐性。通过使用尺寸分离柱和尺寸选择性沉淀，Si NCs 的纯化得到了改善。这些纯化方法以前所未有的方式得到了高度单分散和纯的 Si NCs。这使得科学家能够研究尺寸和表面依赖性的性质和毒性，并使 Si NCs 能够用于生物医学应用。Si NCs 的光学性质很复杂。研究人员使用组合的表征技术，探索了光学性质与尺寸、表面功能化以及制备方法之间的关系。这项工作使人们对 Si NCs 独特的光学性质有了更深入的基本理解。Si NCs 正在被研究用于广泛的重要应用，包括从近红外到黄色可调谐电致发光的 LED、用具有蛋白质端基的胶束封装 Si NCs 以允许对细胞进行靶向体内成像、Si NC-聚合物混合太阳能电池，以及在具有高理论容量和良好电荷保持率的电池阳极中使用 Si NCs。
