石墨烯量子点/CdS/CdSe共敏化太阳能电池

以三维锐钛矿TiO₂微球为上层光散射层材料, 以商业纳米TiO₂为下层连接材料, 采用刮刀法制备了一种新颖的双层TiO₂薄膜, 并应用于量子点敏化太阳能电池(QDSSC)。其中, 石墨烯量子点(GQDs)采用滴液法引入, CdS/CdSe量子点采用连续离子层吸附法(SILAR)制备。采用场发射扫描电镜、透射电镜、X射线衍射、紫外-可见漫反射光谱及荧光光谱对样品进行表征。实验还制备了CdS/CdSe量子点敏化及石墨烯量子点/CdS/CdSe共敏化太阳能电池, 并研究了石墨烯量子点及CdS不同敏化周期及对电池性能影响。研究结果表明, 石墨烯量子点及CdS不同敏化周期对薄膜的光学性质、电子传输及载流子复合均有较大影响。优选条件下, TiO₂/QGDs/CdS(4)/CdSe电池的光电转换效率为1.24%, 光电流密度为9.47 mA/cm², 显著高于TiO₂/CdS(4)/CdSe电池的这些参数(0.59%与6.22 mA/cm²)。这主要是由于TiO₂表层吸附石墨烯量子点后增强了电子的传输, 减少了载流子的复合。     

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.     

Cd^2＋参量对于CdSe／CdS／ZnS量子点荧光特性的影响

测量了CdSe、CdSe／CdS／ZnS量子点的吸收光谱和发射光谱,讨论了两种不同量子点的光谱特性。改变核层内Cd^2＋浓度以及壳层内Cd^2＋／Zn^2＋比例,分别测量多组CdSe／CdS／ZnS量子点发射光谱并计算量子产率,结果表明,Cd^2＋浓度45mmol／L或者Cd^2＋／Zn^2＋比例为1／2时,CdSe／CdS／ZnS量子产率最高,从而确定最佳的Cd^2＋定量参数。     

CdSe量子点的制备及荧光性能改善

主要讨论了CdSe量子点的制备及荧光性能的改善.采用水相合成方法制备了CdSe量子点,并用X射线粉末衍射仪对所合成的量子点进行表征,用荧光分光光度计研究了量子点的荧光性质.结果表明,采用样品处理温度的调节和ZnS壳层的包覆能在一定程度上改善CdSe量子点的荧光性能.     

CdS/CdSe量子点共敏化TiO_2薄膜的光电化学性能研究

采用化学浴沉积法分别将CdS、CdSe量子点沉积在TiO2纳米纤维薄膜上,得到TiO2/CdS/CdSe电极。采用电脉冲沉积法将非晶结构TiO2薄膜插入CdS与CdSe量子点之间,得到TiO2/CdS/a-TiO2/CdSe电极。将两种电极分别组装成太阳能电池,进行光电化学性质研究,结果表明,TiO2/CdS/a-TiO2/CdSe电池的光电转化效率比TiO2/CdS/CdS电池提高了1.68倍。进一步的原因分析结果表明,在CdS与CdSe量子点之间插入TiO2非晶薄膜后,可以极大提高载流子寿命。     

Fe_3O_4/OA/PANI@CdSe/CdS磁性荧光纳米复合物的制备及其表征

由共沉淀法制备出表面羟基化的Fe3O4,并用油酸(OA)进行了修饰。通过新颖简便的微悬浮方法制备出聚苯胺包裹的Fe3O4/OA/PANI。用三步法合成出具有良好的荧光性能的量子点CdSe/CdS。通过EDC交联剂的作用,将量子点CdSe/CdS和Fe3O4连接。该微粒经过透射电子显微镜(TEM)、能谱(EDS)、荧光分光光度计、荧光显微镜和振动样品磁强计(VSM)的表征。结果表明:通过PANI的桥梁作用(静电吸附和氢键作用),量子点CdSe/CdS成功连接到了Fe3O4/OA/PANI表面,得到了磁性荧光复合材料,该材料在药物传递、靶向治疗的应用上都具有很大潜力。     

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。     

Fe_3O_4/CA@CdSe/CdS磁性荧光纳米复合材料的制备及表征

采用共沉淀法制备出Fe3O4,使磁性颗粒表面羟基化,通过柠檬酸(CA)修饰制备得Fe3O4/CA。量子点CdSe/CdS是用三步法合成得到,并用巯基乙酸进行改性,再通过乙二胺偶联剂的作用,将量子点CdSe/CdS和Fe3O4连接。该微粒经过荧光分光光度计、荧光显微镜、透射电子显微镜(TEM)、能谱(EDS)和振动样品磁强计(VSM)的表征。结果表明:通过乙二胺的桥梁作用(静电吸附和氢键作用),量子点CdSe/CdS成功连接到了Fe3O4/CA表面,得到了磁性荧光双功能材料,该材料在药物分离、可视化,靶向治疗等方面的应用都具有很大潜力。     

微波辅助快速合成水溶性CdTe/CdSe核壳量子点

以巯基乙酸(TGA)作为稳定剂,用微波辅助法快速合成了水溶性CdTe/CdSe核壳量子点.比较了传统水热法和微波辅助法制备的量子点性能,研究了加热温度、反应物配比及CdTe量子点浓度对CdTe/CdSe核壳量子点的性能影响.研究结果表明,核壳结构的CdTe/CdSe量子点比单一的CdTe量子点具有更优异的光致发光强度和...     

CdSe胶质量子点的电致发光特性研究

采用胶体化学法合成硒化镉(CdSe)胶质量子点, 在此基础上制成了以CdSe胶质量子点为有源层, 结构为ITO/ZnS/CdSe/ZnS/Al的电致发光(EL)器件. 透射电镜测量表明量子点的尺寸为4.3 nm, 扫描电子显微镜测量ZnS薄膜和Al薄膜结果显示表面均较为平整, 由器件结构的X射线衍射分析观察到了CdSe(111)、ZnS(111)等晶面的衍射, 表明器件中包含了CdSe量子点和ZnS绝缘层材料. 光致发光谱表征胶质量子点的室温发光峰位于614 nm, 电致发光测量得到器件在室温下的发光波长位于450 ~ 850 nm, 峰值在800 nm附近. 本文对电致发光机制及其与光致发光谱的区别进行了讨论.     

Investigation of size dependent structural and optical properties of thin films of CdSe quantum dots

Cadmium selenide (CdSe) quantum dots were grown on indium tin oxide substrate using wet chemical technique for possible application as light emitting devices. The structural, morphological and luminescence properties of the as deposited thin films of CdSe Q-dot have been investigated, using X-ray diffraction, transmission electron microscopy, atomic force microscopy and optical and luminescence spectroscopy. The quantum dots have been shown to deposit in an organized array on ITO/glass substrate. The as grown Q-dots exhibited size dependent blue shift in the absorption edge. The effect of quantum confinement also manifested as a blue shift of photoluminescence emission. It is shown that the nanocrystalline CdSe exhibits intense photoluminescence as compared to the large grained polycrystalline CdSe films.     

不同温度下硒化镉(CdSe)量子点的生长及荧光性研究

研究了以氧化镉（CdO）和硒（Se）粉为前驱体,在三辛基膦（TOP）和油酸中合成无机半导体量子点（quantum dots, QDs）CdSe.研究了在不同的反应温度下粒子的生长,通过紫外吸收光谱（UV-Vis）、荧光发射光谱（PL）、透射电子显微镜（TEM）等手段跟踪反应过程并对样品性能进行了表征.实验结果表明,反应温度和反应时间对量子点的生长和荧光性能有很大的影响.     

Structural,optical and morphological studies of undoped and Zn-doped CdSe QDs via aqueous route synthesis

Undoped and Zn-doped CdSe quantum dots (QDs) were successfully synthesized by the chemical precipitation method. The structural, optical and morphological properties of the synthesized undoped and Zn-doped CdSe QDs were studied by X-ray diffraction (XRD), UV–visible absorption spectroscopy, photoluminescence (PL) spectroscopy, fluorescence lifetime spectroscopy, scanning electron microscopy (SEM), field emission transmission electron microscopy (FE-TEM) and FTIR. The synthesized undoped and Zn-doped CdSe QDs were in cubic crystalline phase, which was confirmed by the XRD technique. From the UV–visible absorption spectral analysis, the absorption wavelengths of both undoped and Zn-doped CdSe QDs show blue-shift with respect to their bulk counterpart as a result of quantum confinement effect. The highest luminescence intensity was observed for CdSe QDs doped with 4% Zn by PL studies. TEM analysis shows that the prepared QDs are spherical in shape.     

CdSe(ZnS) nanocomposite luminescent high temperature sensor

High temperature luminescence-based sensing is demonstrated by embedding colloidal CdSe(ZnS) quantum dots into a high temperature SiO(2) dielectric matrix. The nanocomposite was fabricated by a solution process method. As-prepared CdSe(ZnS) quantum dots in the nanocomposite sensor show an absorption band at a wavelength of 600 nm (2.06 eV). Photoluminescence (PL) measurements show a room temperature emission peak at 606 nm (2.04 eV). The temperature-dependent emission spectra study shows for the first time a CdSe(ZnS)-SiO(2) nanocomposite-based high temperature sensor. The temperature-dependent spectral and intensity modes of the nanocomposite thin film photoluminescence were investigated from 295-525 K. The sensor shows a variation of the emission wavelength as a function of temperature with a sensitivity of ～ 0.11 nm °C( - 1). The film morphology and roughness are characterized using AFM.     

Extracellular biosynthesis of biocompatible CdSe quantum dots

An extracellular biosynthesis method has been developed to prepare cadmium selenide (CdSe) quantum dots (QDs) with strong fluorescence emission by incubating cheap Cd and Se inorganic salts with Escherichia coli (E.coli) bacteria. Ultraviolet–visible absorption spectra, photoluminescence (PL) spectra, and high‐resolution transmission electron microscopy analysis showed that the biosynthesised CdSe QDs have an average size of 3.1 nm, the excellent optical properties with fluorescence emission around 494 nm, and the good crystallinity. It was found that addition of 80 mg of mercaptosuccinic acid resulted in the formation of CdSe QDs with highest PL intensity. Furthermore, Fourier‐transform infrared spectra of as‐synthesised CdSe QDs confirmed the presence of a surface protein capping layer. The biosynthesised CdSe QDs were incorporated into the yeast cells as illustrated by laser confocal scanning microscopy images, showing a great potential in bio‐imaging and bio‐labelling application.Inspec keywords: microorganisms, molecular biophysics, fluorescence, visible spectra, nanofabrication, nanobiotechnology, proteins, cellular biophysics, nanostructured materials, wide band gap semiconductors, cadmium compounds, semiconductor quantum dots, II‐VI semiconductors, transmission electron microscopy, photoluminescence, optical microscopy, ultraviolet spectra, Fourier transform infrared spectra, biological techniques, semiconductor growthOther keywords: biocompatible CdSe quantum dots, extracellular biosynthesis method, cadmium selenide quantum dots, high‐resolution transmission electron microscopy analysis, biosynthesised CdSe QDs, Fourier‐transform infrared spectra, Escherichia coli, ultraviolet‐visible absorption spectra, PL intensity, fluorescence emission, photoluminescence spectra, optical properties, surface protein capping layer, laser confocal scanning microscopy images, bioimaging, biolabelling application, yeast cells, f mercaptosuccinic acid, CdSe     

ODA/TOPO质量比对CdSe量子点性能的影响

采用高温有机金相法,在非配位溶剂中用双配位体系十八胺(ODA)和三辛基氧化磷(TOPO)合成了CdSe量子点(QDs),表征了量子点的形貌,研究了双配位体系中不同ODA与TOPO质量比对CdSe量子点的尺寸分布和荧光量子效率的影响.结果表明,引入ODA后,可制备出分散性良好、形状规则、尺寸分布均匀的CdSe量子点.当ODA与TOPO的质量比为3-4时,量子点的尺寸约为3 nm,光谱半高宽(FWHM)达到最小值29 nm,其量子效率可以达到52.8%-58.1%.     

A novel method for the preparation of water-soluble and small-size CdSe quantum dots

A novel method for the preparation of water-soluble and small-size CdSe quantum dots has been reported under high-intensity ultrasonic irradiation. The as-prepared products have been characterized by absorption spectra, X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM).     

Size tuning of MAA capped CdSe and CdSe/CdS quantum dots and their stability in different pH environments

The present work reports synthesis of mercaptoacetic acid capped CdSe nanoparticles soluble in water at different temperatures and with different precursor ratios. This enabled to tune the particle size of QDs from 2.7 to 5.8 nm. The particles consist of nanocrystals; with mixed phase, hexagonal wurtzite as well as sphalerite cubic and are luminescent with quantum yield 10%. The quantum yield up to 20% has been obtained by growing a shell of CdS over the CdSe. HR-TEM images, XRD patterns and the photoluminescence excitation spectra shows epitaxial growth of CdS shell over CdSe and with average size 3.2 ± 1.2 and 4.7 ± 1.2 nm for CdSe and CdSe/CdS quantum dots respectively. FT-IR spectrum and the negative zeta potential value together confirms the attachment of mercaptoacetic acid to the QD surface, where the carboxylic acid group is facing towards solvent and provides stability due to electrostatic hindrance. Further, the QDs are checked for their stability and the luminescence in environments of different pH (4–11 pH). Both CdSe and CdSe/CdS agglomerate with total elimination of fluorescence for 4 pH medium, and no shift in the fluorescence emission peak observed for the 6–9 pH, therefore QDs can be applicable as the fluorescence tags in this specific range of pH.