不同壳层的CdS／ZnS核／壳结构量子点的温度相关荧光性质

报导了CdS／ZnS纳米晶体（NCs）的制备过程和其光学}生质。通过采用连续离子层吸附和反应技术（SILAR）,我们用少量的表面活性剂合成了不同壳层的四个样品,包括CdS核纳米晶以及具有1～3层ZnS壳的CdS／ZnS核／壳结构纳米晶体样品。发现具有一层ZnS壳的CdS／ZnS样品的荧光量子产率大约比未包覆壳层的CdS纳米晶体样品的强11倍。另外,随着壳层的增加（增至两到三层）,荧光量子产率呈现下降的趋势。对样品进行了温度相关的光谱测量,发现CdS／ZnS和CdS一样具有特殊的光学特性。     

在多相体系中制备核壳型CdSe/ZnS量子点

在多相体系中制得了CdSe/ZnS半导体量子点,采用X射线粉末衍射(XRD)、电子透射显微镜(TEM)等测试手段对产物进行了表征,结果表明CaSe/CdS量子点尺寸均一、形貌规则,具有立方晶体结构.初步研究了此体系的反应机理,并通过紫外-可见吸收光谱和荧光光谱对产物的光学性质进行了分析,结果表明在CASe量子点外面包覆一定厚度的ZnS壳层后,其激子发射强度和量子效率显著提高.     

核壳结构CdS：Mn/ZnS纳米晶的制备与光学性能研究

以3-巯基丙酸为稳定剂,采用共沉淀法在水相中合成了CdS∶Mn掺杂纳米晶,然后进一步将ZnS包覆于CdS∶Mn纳米晶表面,制备了CdS∶Mn/ZnS核壳结构纳米晶。利用X射线衍射（XRD）,透射电子显微镜（TEM）和紫外-可见吸收光谱（UV-Vis）对纳米晶的结构、形貌和光学性质进行了表征,发现制备的纳米晶具有优秀的单分散性,确认合成了CdS∶Mn/ZnS核壳结构纳米晶。通过荧光光谱（PL）研究了纳米晶的发光性质和光稳定性,结果表明包覆壳层后纳米晶的发光强度显著提高,最高可达8倍,且Mn2＋离子的发光峰峰位置随着ZnS壳层数的增加而红移。此外,核壳纳米晶的光稳定性大大提高。     

核壳结构CdS/ZnS@rGA的制备及光催化性能研究

为研究纳米CdS/ZnS@rGA复合材料在可见光下的光催化性能,采用一步溶剂热法合成了以ZnS为壳的CdS/ZnS核壳纳米粒子,将CdS/ZnS核壳纳米粒子附着在rGO纳米片上,并组装成CdS/ZnS@rGA复合气凝胶,用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等对样品进行了表征,通过亚甲基蓝(MB)的光催化降解实验表明：CdS/ZnS@rGA复合气凝胶的形成不仅可以提高CdS的光稳定性,还可以增强对MB吸附能力,同时对MB的降解有明显的促进作用。可见光反应90 min, 50 mg的CdS/ZnS@rGA对100 mL 20 mg/L MB的去除率最高达到99%。经过5次循环实验,该材料仍具有较好的可重复利用性。     

量子点量子阱ZnS/HgS/ZnS/CdS的制备与光学特性

运用湿化学与表面化学方法制备了ＺｎＳ／ＨｇＳ／ＺｎＳ／Ｃｄｓ量子点量子阱（ＱＤＱＷ）结构,以吸收光谱、光致发光及激光谱表征该结构,并研究了外层ＣｄＳ对材料发光特性的影响,首次观测到ＣｄＳ对中间ＨｇＳ阱层发光的增强作用,并归因子隧道效应的存在。     

CuInS2/ZnS核壳结构量子点的水相制备与性能研究

因不含Cd、Pb、Te等有毒元素, 且具有在可见光至近红外光波段可调的发光性能, 铜铟硫(CuInS₂)量子点作为一种新型的I-III-VI型三元半导体材料, 广泛应用于分析检测和生物成像等领域。本研究采用一种低毒低温的方法快速合成CuInS₂量子点及其ZnS核壳结构量子点, 不仅利用ZnS带隙较宽且表面缺陷少的特点, 弥补了CuInS₂量子点的劣势, 提高了CuInS₂量子点的发光性能; 同时由于低毒性ZnS壳层的包覆, 进一步降低生物毒性。当Cu∶In摩尔比为1∶1时, CuInS₂量子点于530 nm处出现明显的发射峰, 且随着In含量的增加, 发光峰逐渐红移。包覆ZnS壳层后, CuInS₂量子点的发光强度明显增大, 且谱峰明显红移。当Cu∶Zn比为1∶1, 回流时间为45 min时, 合成的CuInS₂/ZnS量子点发光性能最优。该合成方法节省能源、生产效率高、绿色环保, 具有较大的应用前景。     

水相中CdSe与核/壳CdSe/CdS量子点的制备与发光特性研究

以巯基乙酸为稳定剂在水相中制备了CdSe与核/壳型CdSe/CdS量子点水溶胶, 用紫外-可见吸收光谱和发射光谱研究了它们的发光特性, 并且用X射线粉末衍射(XRD)、透射电镜(TEM)和X射线光电子能谱(XPS)表征了它们的结构、形貌和化学组成, 结果表明使用该方法制备的量子点分散性良好, 而且用CdS对CdSe进行表面修饰以后的发光强度明显提高, 发射光谱和吸收光谱都有红移现象, 不同粒径颗粒的吸收峰的位置也有所不同.     

CdSe与CdSe/ZnS量子点合成及稀土掺杂

在LSS(liquid-solid-solution)多相体系中制得了CdSe、CdSe/ZnS量子点和Eu掺杂的量子点。利用TEM、XRD、PL、EDS对产物进行了表征。TEM结果显示所得的量子点形貌规则、尺寸均匀。XRD结果显示CdSe/ZnS量子点呈六方晶系。PL结果对比表明,合适厚度壳层ZnS包覆后的CdSe量子点发光效率明显提高,发光峰的半高宽有大幅度提高,并分析了所得的结果。掺杂稀土元素Eu后,CdSe(Eu)量子点在红光区域产生了新的发光峰;而CdSe(Eu)/ZnS量子点在红光区域内没有出现发光峰,并阐明了这种现象的原因。     

CdS量子点沉积的钛基纳米管的制备及其光催化性能研究

采用水热法制备了钛基纳米管,利用双官能团物质2-巯基丙酸为连接剂,将CdS量子点沉积在纳米管表面,研究了2-巯基丙酸浓度对样品的物相、微观结构和光催化活性的影响。利用X射线衍射仪、透射电子显微镜、紫外可见分光度计和光催化反应仪对样品进行了表征。结果表明,CdS量子点成功沉积在纳米管表面,改变2-巯基丙酸浓度可以调节CdS量子点的沉积数量,随着CdS量子点在纳米管表面的沉积,样品不仅在紫外光区有吸收,在可见光区也出现吸收,其吸收边在540nm左右。CdS量子点的沉积提高了样品在可见光下的光催化活性,2-巯基丙酸浓度为0.7mol/L时制备的样品对甲基橙降解的光催化活性最好。     

水溶性ZnS量子点的共沉淀法制备、 表征及其光学性能

以硫化钠和乙酸锌为反应物,3-巯基丙酸为表面包覆剂,利用共沉淀法制备了水溶性ZnS量子点。并采用X射线衍射仪、透射电子显微镜和荧光分光光度计等对样品的结构、形貌、粒径和光学性能进行了表征。结果表明:所得样品为ZnS立方型闪锌矿结构,量子点的形状呈不规则球形,粒径主要集中在4.8nm左右;样品在585～590nm之间出现了黄色荧光发射波峰。同时,利用红外光谱对ZnS量子点的合成机理进行了初步分析。     

Preparation of lanthanide doped CdS, ZnS quantum dots in natural polysaccharide template and their optical properties

Employing a biomimic method using polysaccharide as template, luminescent lanthanide ions doped CdS and ZnS quantum dots (QDs) were prepared. According to the results of TEM and absorbance, nanocrystals with an average size of 6 nm were formed under mild condition without any toxic and expensive agent applied. Differentiating from the un-doped CdS and ZnS QDs prepared in polysaccharide template, the lanthanide doped QDs exhibited obvious dopant emission in their photoluminescence spectrum. It was also found that the dopant PL became more prominent with increasing lanthanide doping concentration, while the highest PL intensity was obtained at a doping level of 1% for both of CdS and ZnS QDs. When different lanthanide ions were introduced into the CdS QDs in polysaccharide template, varied emission wavelength were able to be obtained. This study provides an easy, mild and environmental friendly alternative method to prepare doped quantum dots. In addition, the bioactivity and processabilities endowed by the polysaccharide template may expand the applications potential of this type of optical materials.     

Highly luminescent blue emitting CdS/ZnS core/shell quantum dots via a single-molecular precursor for shell growth

Highly luminescent blue-emitting CdS/ZnS core/shell quantum dots (QDs) were synthesized in N-oleoylmorpholine by two facile steps: first, the CdS core QDs were prepared via a simple one-pot method involving a direct reaction of Cd precursor cadmium stearate and S precursor S powder in solvent N-oleoylmorpholine; second, ZnS shells were successively overcoated on CdS core through the decomposition of single molecular precursor zinc diethyldithiocarbamate. The thickness of shell was precisely tuned by controlling drip feed speed and amount of shell precursor. The obtained CdS/ZnS core/shell QDs showed the maximum photoluminescent quantum yield of 54.8% and narrow spectra bandwidth, exhibiting high monodispersity, good color purity and long fluorescent lifetimes. The CdS/ZnS core/shell QDs with tunable emission wavelength of 424–470 nm were obtained by controlling the thickness of ZnS shell overgrown on different-sized CdS QDs, which are promising materials for blue light-emitting devices.     

High color rendering index white LED based on nano-YAG:Ce3+ phosphor hybrid with CdSe/CdS/ZnS core/shell/shell quantum dots

To improve the poor color rendering index (CRI) of YAG:Ce-based white light-emitting diode (LED) due to the lack of red spectral component, core/shell/shell CdSe/CdS/ZnS quantum dots (QDs) were synthesized and blended into nano-YAG:Ce³⁺ phosphors. Prominent spectral evolution has been achieved by increasing the content of QDs. A white LED combining a blue LED with the blends of nano-YAG phosphors and orange- and red-emission QDs with a weight ratio of 1:1:1 was obtained. This kind of white LED showed excellent white light with luminescent efficiency, color coordinates, CRI and correlated color temperature (CCT) of 82.5?lm/W, (0.3264, 0.3255), 91 and 4580?K, respectively.     

CdSe／CdS核壳量子点拉曼光谱的表面模分析

研究了不同壳层厚度(0～5.5ML)的CdSe/CdS核壳量子点的一次和高次拉曼散射,具体分析了CdSe和CdS的表面模随着壳层厚度的变化情况.结果表明,随着壳层厚度的增加,CdSe表面模(SO1)从198cm-1频移到185cm-1,CdS的表面模(SO2)从275cm-1频移到267cm-1,并且SO1和SO2试验结果与由介电连续模型得到的理论值很接近.此外,根据CdSe表面模的频移,对随着CdS壳层厚度的增加而引起的核层(CdSe)的介电常数随环境的变化做出了修正.     

Synthesis of highly photo-stable CuInS2/ZnS core/shell quantum dots

CuInS₂ quantum dots are considered near-ideal fluorophores based on their bright emission and low toxicity. However, CuInS₂ quantum dots are still bothered by their sensitivity to surface chemistry and chemical environment. Traditionally, the CIS QDs require an additional coating process to be encapsulated inside silica sphere or organic polymer. Up till now, few works have been made concerning improving the intrinsic stability of CIS QDs. In an effort to improve the stability of CuInS₂ quantum dots, we came up with a new method by increasing the ZnS shell thickness. These QDs were characterized by photoluminescence, HRTEM, XRD and XRF analysis. We investigated the influence of ZnS shell thickness on the ambient stability of CIS/ZnS QDs. The results demonstrated that a thicker ZnS shell helped significantly improve both photostability and chemical stability of the QDs. Finally, the thick shell QDs were dispersed into transparent polymer matrix and fabricated into a LED device, which also gave much more stability compared with conventional QDs.     

CdSe and CdSe/ZnS quantum dots for the detection of C-reactive protein

In this study, a method for the detection of C-reactive protein (CRP) using CdSe and CdSe/ZnS quantum dots (QDs) is proposed. CdSe and CdSe/ZnS core-shell QDs are synthesised by using 2-mercaptosuccinic acid (MSA) as a capping agent. These QDs were then subjected to various characterisation studies, namely X-ray diffraction and transmission electron microscope for size and structure, Fourier transform infrared spectroscopy for the confirmation of functional groups, ultraviolet–visible absorption and fluorescence spectroscopy for optical characteristics and dynamic light scattering for hydrodynamic changes of QDs. Two biochemical mixtures were developed: one by mixing blood serum containing CRP and CdSe-phosphorylethanolamine (PEA) and the other by mixing blood serum with CdSe/ZnS-PEA. When these mixtures are observed for fluorescence due to interaction of QDs with CRP, a correlation between changes in fluorescence for different concentrations of CRP is noted. The result demonstrates that CRP can be detected with the help of QDs without using any antibodies.     

Two-fold emission from the S-shell of PbSe/CdSe core/shell quantum dots

The optical properties of PbSe/CdSe core/shell quantum dots with core sizes smaller than 4 nm in the 5-300 K range are reported. The photoluminescence spectra show two peaks, which become increasingly separated in energy as the core diameter is reduced below 4 nm. It is shown that these peaks are due to intrinsic exciton transitions in each quantum dot, rather than emission from different quantum dot sub-ensembles. Most likely, the energy separation between the peaks is due to inter-valley coupling between the L-points of PbSe. The temperature dependence of the relative intensities of the peaks implies that the two emitting states are not in thermal equilibrium and that dark exciton states must play an important role.     

ZnS/CdS单带差超晶格薄膜的制备及光学性质研究

为了提高CdTe太阳电池的效率,ZnS/CdS单带差超晶格被创新性地提出.用射频磁控溅射法制备了ZnS/CdS单带差超晶格薄膜,用SEM观察样品截面,分层清晰;测试了ZnS/CdS单带差超晶格薄膜的透过谱图,在300～800nm波长范围内存在4个明显的透过峰.相较于CdS单层膜与ZnS单层膜,ZnS/Cds单带差超晶格薄膜在可见光短波部分的光谱响应十分明显,说明Zns/Cds单带差超晶格薄膜的电子能带与光子吸收方式发生了明显的变化.理论上可以提高CdTe太阳电池的效率.