硅纳米晶体表面改性和发光性能研究

发布时间：2018-01-17 01:10

本文关键词：硅纳米晶体表面改性和发光性能研究　出处：《浙江大学》2015年硕士论文　论文类型：学位论文

【摘要】：硅纳米晶体由于具有新颖的电学和光学性能,在光电子、光伏、显示和生物标记等领域拥有广阔的用途前景。本论文的工作,集中在研究硅纳米晶体的发光性能与其尺寸和表面改性的关系。我们采用冷等离子体硅纳米晶体合成设备获得独立存在的,尺寸分布在2-10 nm的硅纳米晶体颗粒。然后,对其进行氢化硅烷化表面改性,尺寸分选等操作,获得尺寸分布集中的一系列颗粒。测试这一系列颗粒的荧光光谱,荧光效率,荧光寿命并以此计算其辐射,非辐射复合几率。我们发现荧光峰位能量与尺寸之间符合有效质量近似模型。荧光效率随着尺寸的减小(从10 nm减小到2 nm)呈先升高后下降的趋势,最佳荧光效率出现在尺寸2.8nm时,对应的荧光峰位是744 nm。随着尺寸从10 nm减小到2 nm,我们发现硅纳米晶体的非辐射复合几率呈指数型上升,通过电子顺磁能谱(EPR)测试,我们证明这与纳米晶表面悬挂键密度的变化有关。当尺寸从10 nm减小到2.8 nm,硅纳米晶体的辐射复合几率也呈现指数型上升,这符合量子限域效应理论。然而,当尺寸进一步从2.8 nm减小到2 nm时,辐射复合几率不再呈现指数型上升,而是略有下降。我们认为,当纳米晶体尺寸很小时,电子和空穴容易从纳米晶体内部隧穿到其表面,这可能是造成辐射复合几率不再呈现指数型上升的原因。我们比较了加热法和紫外(UV)辐照法对硅纳米晶体氢化硅烷化反应的影响,选用1-十八烯,1-十二烯,1-辛烯,1-戊烯和苯乙烯进行氢化硅烷化反应。获得了不同改性条件下的烷基钝化的硅纳米晶体。对其进行尺寸,荧光光谱,荧光效率,荧光寿命等测试,并计算其辐射,非辐射复合几率。我们发现,UV辐照法有利于降低氢化硅烷化反应过程中基团的交联反应。对于1-十八烯,1-十二烯,1-辛烯,采用UV辐照法和加热法获得的硅纳米晶体具有相似的发光性能；而对于1-戊烯和苯乙烯,相对于加热法,采用UV辐照法更有利于提高硅纳米晶体的荧光效率。我们对氢化硅烷化的硅纳米晶体进行了电子顺磁能谱测试,发现较高的荧光效率对应于较低的表面悬挂键密度。
[Abstract]:Because of its novel electrical and optical properties, silicon nanocrystals have broad application prospects in photoelectron, photovoltaic, display and biomarker fields. Focusing on the study of the relationship between the luminescence properties of silicon nanocrystalline and its size and surface modification, we use the cold plasma silicon nanocrystalline synthesis equipment to obtain independent existence. The size distribution of silicon nanocrystalline particles is 2-10 nm. Then, the hydrosilanized surface modification, size sorting and other operations are carried out. The fluorescence spectra, fluorescence efficiency, fluorescence lifetime of these particles were measured and their radiation was calculated. Non-radiative recombination probability. We found that the fluorescence peak energy and size fit the effective mass approximation model. The fluorescence efficiency decreases with the size (from 10 nm to 2 nm). It showed a tendency of rising first and then decreasing. The optimum fluorescence efficiency is at the size of 2.8 nm, and the corresponding fluorescence peak is 744 nm, which decreases from 10 nm to 2 nm. We found that the non-radiative recombination probability of silicon nanocrystalline increased exponentially, and was measured by electron paramagnetic energy spectroscopy (EPR). It is shown that this is related to the change of the hanging bond density of nanocrystalline surface. When the size is reduced from 10 nm to 2.8 nm, the radiation recombination probability of silicon nanocrystals also increases exponentially. However, when the size is further reduced from 2.8 nm to 2 nm, the radiation recombination probability does not increase exponentially, but decreases slightly. When the size of nanocrystalline is very small, electrons and holes are easily tunneled from the inside of nanocrystalline to its surface. This may be the reason that the probability of radiation recombination no longer increases exponentially. We compared the effects of heating and UV irradiation on the hydrogenation of silicon nanocrystalline with 1-18 enene. 1-12 alkyl passivated silicon nanocrystals were obtained by hydrogenation of 1-12-octene-1-pentene with styrene. The size, fluorescence spectrum and fluorescence efficiency of these crystals were determined. The fluorescence lifetime was measured and the recombination probability of radiation and non-radiation was calculated. We found that UV irradiation was beneficial to reduce the cross-linking reaction of groups in the process of hydrosilanization. The Si nanocrystals obtained by UV irradiation and heating have similar luminescence properties. For 1-pentene and styrene, UV irradiation is better than heating method to improve the fluorescence efficiency of silicon nanocrystalline. We have measured the electron paramagnetic energy spectrum of hydrogenated silanized silicon nanocrystals. It is found that the higher fluorescence efficiency corresponds to the lower surface hanging bond density.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O613.72

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