Silicon Nanochemistry

研究的重点集中在新型硅纳米晶体上。灵感来自于我们新发现的将多分散硅纳米晶体分离成1-5纳米范围内的单分散部分的能力，这使得首次记录测量和评估硅纳米晶体的尺寸依赖性化学，物理和生物特性成为可能。我们提出的未来研究将通过四个主题扩展和丰富这些重大进展。第一个重点是合成一类具有氧化还原活性官能团的新型硅纳米晶体，这些官能团化学地拴在纳米晶体表面。这将使硅纳米晶体的表面电荷以及电学和光学性质能够通过化学和/或电化学手段进行微调。原型ncSi:R将由氧化还原活性官能团R组成，通过与烯烃或炔的氢硅化反应，共价地附着在氢化物端端纳米晶硅前驱体ncSi:H的表面。通过化学或电化学控制ncSi核芯表面上覆盖R基团的氧化（p,q）的数量和程度，可以使被覆盖的硅纳米晶体转化为ncSi:(1-p)R。pRq，其中R将从金属茂物Cp2M， M = V, Cr, Mn, Fe, Co, Ni，配位化合物RuBipy，芳烃Ar和富勒烯C60中选择。该项目的主要目标是证明硅纳米晶体的电学和光学特性的氧化还原调谐。第二个重点是“裸”硅纳米晶体的合成，没有表面有机物，具有可控的表面电荷和胶体稳定性，这将提供无与伦比的接触硅核的化学和物理性质，不受表面有机物的阻碍。在本项目中，原型[ncSi+]]X-]将使用HBF4等试剂，由氢化物或氯化物覆盖的前体ncSi:H或ncSi:Cl合成。Et2O BH3。THF和AgPF6分别形成电荷稳定的[ncSi+][BF4-]， [ncSi+][BH4-]和[ncSi+][PF6-]。掺杂的第三个主要集中在合成和表征形式的nanosilicon使用射频等离子体激发的SiH4-PH3 SiH4-B2H6气态的混合物以及高频/ H2O / FeCl3 n型和P型硅晶片的蚀刻,项目的目标是B的掺杂剂浓度和空间位置的确定和P ncSi掺杂物,电荷传输测量,光学和光电性质的n型和P型ncSi电影以及电影ncSi pn结,有可能实现新一代ncSi设备。第四是建立在胶体稳定的纳米晶体“硅墨水”用于制造可印刷的多色光电器件的设想用途上。目的是学习如何定制硅纳米晶体的尺寸和表面，以控制其在极性和非极性溶剂中的溶解度，增强其电荷输运特性，微调其波长，并最大化其在可见光谱范围内的光致发光和电致发光效率，以优化多色硅发光二极管的稳定性和性能。

The focus of the research centers on new classes of silicon nanocrystals. The inspiration stems from our newfound ability to separate ensembles of poly-dispersed silicon nanocrystals into mono-dispersed fractions in the range of 1-5 nm, which has enabled the first recorded measurement and evaluation of the size-dependent chemical, physical and biological properties of silicon nanocrystals. Our proposed future research will expand and enrich upon these significant advances through four main themes. The first focuses on the synthesis of a novel class of silicon nanocrystals with redox active functional groups chemically tethered to the nanocrystal surface. This will enable the surface charge and hence electrical and optical properties of the silicon nanocrystals to be fine-tuned by chemical and/or electrochemical means. The archetype ncSi:R will be comprised of a redox active functional group R covalently attached to the surface of a hydride-terminated nanocrystalline silicon precursor ncSi:H via hydrosilation with an alkene or alkyne. Through chemical or electrochemical control of the number and extent of oxidation (p,q) of the capping R groups on the surface of the ncSi core the capped silicon nanocrystals can be transformed to ncSi:(1-p)R.pRq, where R will be chosen from metallocenes Cp2M, M = V, Cr, Mn, Fe, Co, Ni, coordination compounds RuBipy, aromatics Ar and fullerenes C60. The primary goal of this project is to demonstrate redox tuning of the electrical and optical properties of silicon nanocrystals. The second focuses on the synthesis of ‘naked’ silicon nanocrystals, devoid of surface organics, with controlled surface charge and colloid-stability, which will provide unparalleled access to the chemical and physical properties of the silicon core unimpeded by surface organics. In this project the archetypes [ncSi+]]X-] will be synthesized from the hydride or chloride capped precursors ncSi:H or ncSi:Cl using reagents, such as HBF4.Et2O, BH3.THF and AgPF6 to form charge-stabilized [ncSi+][BF4-], [ncSi+][BH4-] and [ncSi+][PF6-], respectively. The third focuses on the synthesis and characterization of doped forms of nanosilicon using radio-frequency plasma excitation of SiH4-PH3 and SiH4-B2H6 gaseous mixtures as well as HF/H2O/FeCl3 etching of n- and p-doped Si wafers, the goal of the project being determination of the dopant concentration and spatial location of B and P dopants in the ncSi, measurement of charge transport, optical and optoelectronic properties of n- and p-doped ncSi films as well as films with ncSi p-n junctions, potentially enabling new generation ncSi devices. The fourth is founded upon the envisioned utility of colloidally-stable nanocrystal ‘silicon inks’ for the fabrication of printable multicolor optoelectronic devices. The objective is to learn how to tailor the sizes and surfaces of silicon nanocrystals to control their solubility in polar and non-polar solvents, enhance their electrical charge transport properties, fine-tune their wavelength, and maximize their photoluminescence and electroluminescence efficiency across the visible spectral range, to optimize the stability and performance of multicolor silicon light emitting diodes, SiLEDs.