Ⅰ-Ⅲ-Ⅵ族半导体纳米晶

半导体纳米晶是近年来发展起来的一类新型功能材料,因其独特的量子限域效应和光电性质,在太阳电池、发光二极管、光电探测器、生物标记、非线性光学等领域中具有潜在的应用。与目前研究比较多的Ⅱ-Ⅵ和Ⅳ-Ⅵ族纳米晶相比,Ⅰ-Ⅲ-Ⅵ族半导体纳米晶,不含镉和铅等重金属元素,具有毒性小、带隙窄、光吸收系数大、Stokes位移大、自吸收小以及发光波长在近红外区等特点,有望成为新一代低成本太阳电池和低毒荧光量子点生物标记材料, 还可用于发光二极管和光电探测等领域。因此,Ⅰ-Ⅲ-Ⅵ族半导体纳米晶的合成、性质及应用研究成为近期纳米晶研究领域的热点之一。本文将综述Ⅰ-Ⅲ-Ⅵ族半导体纳米晶的研究进展,着重介绍其制备方法、光学性质及其在生物标记、太阳电池等领域的应用。     

II-VI族半导体荧光纳米微粒及复合荧光微球的制备及应用

本文简单介绍了半导体荧光纳米微粒（又称量子点）的基本概念和荧光性质，评述了II－VI族半导体荧光纳米微粒（NCs）的制备和性质研究进展，尤其对基于荧光纳米微粒的复合荧光微球的制备、性质及改进方法进行了详细的讨论，指出目前存在问题和发展方向。     

叶酸受体靶向CdS量子点应用于HepG2细胞成像研究

0引言量子点(quantum dots,QDs)又称半导体纳米晶体(semiconductor nanocrystal),是一种由Ⅱ-Ⅵ族或Ⅲ-Ⅴ族元素组成的尺寸在2￣20nm之间,稳定的微     

CdSe的电子结构和光学性质研究

CdSe是Ⅱ-Ⅵ族半导体材料中一种重要的半导体材料,它有闪锌矿和纤锌矿两种不同的结构,带隙较窄,具有优良的电光特性和广泛的应用前景,得到了人们的广泛关注[1-3].     

溶剂热合成法制备(Zn,Hg)S微晶和薄膜

近年来，由于Ⅱ～Ⅵ族半导体纳米材料的特殊物理、化学性质及其在半导体、光学器件、激光二极管、IR探测器等方面的广泛应用，它们的制备和表征引起了人们越来越大的兴趣犤１～１１犦。现在（Zn，Hg）S微晶正被广泛而深入的研究和应用。例如：一种发蓝光的激光二极管已经设计成功，它包含一夹在两衬层间的活性层，无论是在衬层还是在活性层中都包含有（Zn，Hg）S犤５犦。Sugao也曾报道过一种以（Zn，Hg）S为基础的半导体激光器件犤６犦。Parkin曾用MCl２（M＝Zn，Cd，Hg）和Li２E（E＝O，S，Se，Te）混合热解法制备ME或MxM'yS…     

Ⅰ-Ⅲ-Ⅵ族量子点的制备及其在照明显示领域的应用

半导体量子点因其独特的光电性质, 在发光二极管、太阳能电池和生物标记等领域展现出广阔的应用前景。传统的Ⅱ-Ⅵ和Ⅲ-Ⅴ族二元量子点具有优异的发光性能, 但其所含的Cd、Pb等有毒重金属元素极大制约了大规模商业应用。Ⅰ-Ⅲ-Ⅵ 族多元量子点作为近年来兴起的一类新型荧光材料, 其具有无毒、带隙可调、Stokes位移大、荧光寿命长等特性, 被认为是替代传统二元量子点的理想材料, 因此成为了科研工作者研究的热点。本文详细介绍了Ⅰ-Ⅲ-Ⅵ 族量子点的研究进展, 从该类量子点的基本性质出发阐明其光学性能的调控机制, 重点介绍了近年来该类量子点的有机相及水相制备技术, 对其在照明显示领域应用的研究进展进行了总结, 并与其他类型量子点器件的最新研究现状进行了对比。最后, 分析了Ⅰ-Ⅲ-Ⅵ 族量子点发展过程中有待解决的主要问题, 并对其今后的发展方向进行了展望。     

纳米ZnS,CdS水热合成及其表征

纳米ＺｎＳ、ＣｄＳ水热合成及其表征苏宜，谢毅，陈乾旺，钱逸泰（中国科学技术大学应用化学系合肥２３００２６）关键词硫化锌，硫化镉，水热技术ⅡＢ～ⅥＡ族化合物是主要的半导体发光材料，广泛应用于各种发光与显示装置［１］可采用气相反应、固气相反应及液相反应等...     

一种基于ZnO纳米棒阵列膜的H_2O_2传感器

氧化锌(ZnO)是Ⅱ-Ⅵ族半导体氧化物,作为一种重要的宽禁带半导体材料,用途十分广泛.当ZnO尺寸达到纳米级别时,展现出许多优异的、特殊的性质,如无毒和非迁移性、荧光性、压电性、吸收和散射紫外线能力等,因而备受研究者的关注~([1]).     

硒化铜/硒化锌复合物的制备及性能表征

<正>硒化物半导体具有可控的形貌和相结构，在热电、激光、光学滤波器、太阳能电池和传感器等领域有着广泛应用。1996年，美国劳伦斯利弗莫尔国家实验室的研究人员首次提出并验证了过渡金属元素表面掺杂Ⅱ-Ⅵ族半导体晶体作为中红外激光增益介质的可能性。经过表面修饰的Ⅱ-Ⅵ族半导体材料具有优异的中红外光学性能，已经投入工业生产^[1]。2000年，铜掺杂硒化锌(Cu:ZnSe)半导体纳米晶体被首次报道(量子产率2%～4%)^[2]。2005年，彭笑刚团队^[3]将掺杂方法分为生长掺杂和成核掺杂两种，并采用生长掺杂法制备了高质量的Cu:ZnSe量子点(量子产率10%～30%)，该量子点会发出明亮的翠绿色光。然而，上述材料的合成路线对环境有害，在生物医药领域并不适用。2006年，中国科学院某实验室采用宽带隙的ZnSe修饰硒化镉(CdSe)纳米粒子，可以有效地去除CdSe表面缺陷^[4]。     

有机体系中Ⅱ-Ⅵ族量子点的制备及其合成机理

量子点由于其量子效应而具有既不同于体相材料又有别于一般分子的优异光学性能,因此在生物医学领域,特别是在生物标记中具有良好的应用前景.Ⅱ-Ⅵ族量子点由于其荧光发射波长几乎覆盖了整个可见光区而引起人们的关注,其中在有机体系中合成油溶性Ⅱ-Ⅵ族量子点具有反应产物稳定,量子产率高,并且可以制备性能更加优异的核.壳结构的量子点(CdSe/ZnS,CdSe/CdS等)等优点,因此在过去的十几年中被广泛而深入地研究.本文重点综述了在有机体系中,单分散、高荧光性能Ⅱ-Ⅵ族量子点的制备方法--高温热解法及其合成机理的研究进展,并对今后的研究方向作了展望.     

Luminescence 3D-ordered porous materials composed of CdSe and CdTe nanocrystals

The luminescence porous materials of CdTe or CdSe nanocrystals (NCs) were prepared by filling the corresponding NCs into the voids of colloidal crystal by co-deposition of polymer beads and NCs. After removing the beads with tetrahydrofuran (THF), the 3D-ordered porous materials of CdTe (or CdSe) NCs were obtained. The wavelength of maximum photoluminescence of the NCs porous material shows obvious red shift compared with their aqueous dispersion. Under the excitation of high-energy electron the porous materials of CdTe and CdSe NCs will emit photons that can be collected to form a cathode luminescence (CL) image.     

Characterization of CdSe nanocrystals coated with amphiphiles. A capillary electrophoresis study

We have synthesized CdSe nanocrystals (NCs) possessing a trioctylphosphine surface passivation layer and modified with amphiphilic molecules to form a surface bilayer. The NCs covered with single amphiphiles are not stable in aqueous solution, but a mixed amphiphilic system is shown to provide stability in solution over several months. The solutions of the modified NCs were characterized by UV-Vis absorbance, photoluminescence, and transmission electron microscopy. An electrophoretic study revealed two operational modes. The first relies on the enrichment of NCs using a micellar plug as a tool. The accumulation of NCs at the plug-electrolyte buffer interface results in a sharp peak. By controlling the electrophoretic conditions, nanocrystals were forced to exit a micellar plug into an electrolyte buffer. We conclude that a system consisting of modified nanocrystals and a micellar plug can act as a mixed pseudomicellar system, where modified nanocrystals play the role of pseudomicelles.FigureElectrophoretic focusing of amphiphile coated CdSe nanocrystals using a micellar plug. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00604-011-0727-8) contains supplementary material, which is available to authorized users.     

Comparative study on coating CdSe nanocrystals with surfactants

We have synthesized CdSe nanocrystals (NCs) in sizes from 2.2 to 5.1 nm passivated with hydrophobic trioctylphosphine oxide (TOPO) in combination trioctylphosphine (TOP) or tributylphosphine (TBP) to obtain particles of the type CdSe/TOPO/TOP or CdSe/TOPO/TBP. These NCs were then dispersed in aqueous solution of ionic or non-ionic surfactants (such as stearate, oleic acid, Tween) using a biphase (water and chloroform or hexane) transfer method. It is found that both the structure of the surfactant and the native surface of the ligand govern the coating of the NCs with surfactants. More specifically, the hydrophobicity-hydrophilicity balance of the surfactant regulates the coating efficacy, thereby transferring the NC from the organic to the aqueous phase. The type of ligand on the NCs and the kind of coating surfactant also affect photoluminescence (PL). The ratio of PL and absorbance unit (defined as PL per 0.1 AU) was implemented as a tool to monitor changes in PL intensity and wavelength as a function of size, coatings and surface defects. Finally, the distribution of CdSe nanocrystals between pseudophases in cloud point extraction was discussed based on experimental results. It was concluded that the size of CdSe nanocrystal present in an appropriate pseudophase is correlated with the way in which the non-ionic surfactant coats CdSe nanocrystals.

Ligand effects on optical properties of CdSe nanocrystals

We report effects of various organic and inorganic ligands on optical properties of CdSe nanocrystals (NCs) by changes in their photoluminescence and absorbance spectra. Surface ligand loss occurring during dilution and purification of solutions of CdSe NCs leads to a decrease of photoluminescence intensity. The complex of trioctylphosphine with Se atoms on the surface of CdSe NCs is found responsible for the trap emission band that is red-shifted relative to the photoluminescence band edge.     

Hierarchical CdSe-gold hybrid nanocrystals: synthesis and optical properties

The synthesis of hybrid nanostructures with controlled size, shape, composition and morphology has attracted increasing attention due to the fundamental and applicable interest. Here, we demonstrate the synthesis and optical properties of hierarchical CdSe-Au hybrid nanostructures with zinc blende (ZB) CdSe nanocrystals (NCs). For 3.5 nm ZB CdSe NCs, one Au cluster was deposited on each CdSe NC. Nevertheless, several Au clusters were selectively deposited on the apexes of 5 nm and 8 nm ZB CdSe NCs, resulting from the different reactivity of crystal facets. Furthermore, hierarchical CdSe-Au nanostructures with complex morphology were organized with the isolated CdSe-Au hybrid NCs by the coalescence of Au domains on the CdSe-Au hybrid NCs. UV-Vis spectra revealed a red tail upon the deposition of Au clusters. The chemical joint of Au on CdSe NCs was further confirmed by fluorescence quenching. The optical limiting performance of CdSe-Au hybrid NCs dispersed in toluene was investigated at 532 nm using a Nd:YAG laser with the pulse width of 8 ns.     

Capillary electrophoretic separation of nanoparticles

In the present work, CdSe nanocrystals (NCs) synthesized with a trioctylphosphine surface passivation layer were modified using amphiphilic molecules to form a surface bilayer capable of providing stable NCs aqueous solutions. Such modified nanocrystals were used as a test solute in order to analyze new electrophoretic phenomena, by applying a micellar plug as a separation tool for discriminating nanocrystals between micellar and micelle-free zones during electrophoresis. The distribution of NCs between both zones depended on the affinity of nanocrystals towards the micellar zone, and this relies on the kind of surface ligands attached to the NCs, as well as electrophoretic conditions applied. In this case, the NCs that migrated within a micellar zone can be focused using a preconcentration mechanism. By modifying electrophoretic conditions, NCs were forced to migrate outside the micellar zone in the form of a typical CZE peak. In this situation, a two-order difference in separation efficiencies, in terms of theoretical plates, was observed between focused NCs (N ~ 10⁷) and a typical CZE peak for NCs (N ~ 10⁵). By applying the amino-functionalized NCs the preconcentration of NCs, using a micellar plug, was examined, with the conclusion that preconcentration efficiency, in terms of the enhancement factor for peak height (SEF_height) can be, at least 20. The distribution effect was applied to separate CdSe/ZnS NCs encapsulated in silica, as well as surface-modified with DNA, which allows the estimation of the yield of conjugation of biologically active molecules to a particle surface.     

Efficient functionalization of aqueous CdSe/ZnS nanocrystals using small-molecule chemical activators

Small molecular reagents that can efficiently functionalize water soluble CdSe/ZnS nanocrystals (NCs) are reported. These reagents do not cause quenching or precipitation of NCs as seen with commercially available activators. The results demonstrate that controlling the electrostatic character of the materials is critical in the design of functionalization schemes.     

Improving the Power-Conversion Efficiency through Alloying in Common Anion CdZnX (X=S,Se) Nanocrystal Sensitized Solar Cells

In this paper, we have investigated the possibility of utilizing CdZnS and CdZnSe alloy nanocrystals (NCs) as sensitizers in quantum-dot solar cells (QDSCs). The alloy NCs were synthesized by a high-temperature hot injection method and subsequently characterized through high photoluminescence quantum yield, along with larger size compared to binary NCs. Femtosecond transient absorption measurements revealed long-lived charge carriers in the alloy structure due to more structural rigidity and less defect states. Finally, the solar-cell efficiencies of the CdZnS (CdZnSe) NCs were found to be 3.05 % (3.69 %) as compared to 1.23 % (3.12 %) efficiencies for CdS (CdSe) NCs. Thus, common anion ternary NCs have been successfully utilized for solar-cell assembly and can be helpful for constructing tandem solar cells to harvest the high-energy portion of solar radiation.     

Hyperbranched polymers meet colloid nanocrystals: a promising avenue to multifunctional,robust nanohybrids

Colloid nanocrystals (NCs) mainly include metal nanocrystals, semiconductor nanocrystals, and insulator nanocrystals, exhibiting interesting size-dependent electrical, optical, magnetic, and chemical properties that cannot be achieved by their bulk counterparts. However, there’s a critical problem that NCs tend to aggregate, which induces degradation of their performance. Hyperbranched polymers (HPs) possess excellent attributes of three-dimensional topology, low viscosity, good solubility, and plenty of modifiable terminal groups. The combination of NCs and HPs to form nanohybrids cannot only endow NCs with multifunctionality, uniform dispersibility, and splendid solubility but also can impart extra properties to HPs. This article reviews the recent progress and state-of-the-art of the synthesis and applications of NCs-HPs nanohybrids (NHBs). NHBs can be obtained by three approaches: HPs first (i.e., NCs are formed with the stabilizer of HPs), NCs first (i.e., HPs are grafted on the surface of as-prepared NCs), and ligand exchange (the original ligand of NCs is replaced with HPs). Various HPs including hyperbranched poly(amidoamine), polyethylenimine, polyglycerol, polyester, polyamide, polyurethane, and poly(3-ethyl-3-hydroxymethyloxetane), as well as sorts of NCs such as metals (e.g., Ag, Au, Pd, Pt, and Rh), quantum dots (e.g., ZnO, CdS, CdTe, CdSe, and SnO₂), magnetic oxides (e.g., Fe₃O₄), rare earth compounds, and so forth, have been used to obtain NHBs. The NHBs can be applied in nanocatalysis, antimicrobia, biosensor, biological labeling, and other fields promising their bright future.