不同环境因素对水热法合成碲化镉量子点的影响

对比了不同巯基稳定剂和前体浓度对水热环境CdTe量子点的生长过程和光物理性质的影响。结果表明,巯基丙酸与镉前体的结合能力较强,一定程度上减小了前体溶液中镉的浓度,故CdTe量子点生长速率较慢;空间位阻较大的硫普罗宁与镉前体的结合相对较弱,因此导致CdTe量子点生长较快。巯基丙酸有利于制备发光波长较短的高荧光强度CdTe 量子点,而硫普罗宁有利于制备发光波长较长的高荧光强度CdTe量子点。前体浓度对CdTe量子点的生长速率和光物理性质的影响不明显。在上述实验结果基础上,考察了水溶性乙酸钠和聚丙烯酸钠电解质对水热环境中CdTe量子点的生长过程和光物理性质的影响。结果表明,添加乙酸钠后可提高CdTe量子点的生长速率,进而导致CdTe量子点的表面重构和钝化能力下降,使荧光强度降低;聚丙烯酸钠对镉单体独特的固定作用导致CdTe量子点生长缓慢,尺寸集中化受限,钝化能力降低,使荧光强度下降更加明显。     

水溶性CdTe量子点的合成及影响因素研究

本文以巯基乙酸(TGA)为稳定剂,在水相中合成了高荧光CdTe量子点.其荧光发射波长在507 ～ 628nm范围内可调,最窄半峰宽37 nm,粒径约3.4nm,量子产率达42.1％.本实验在固定前躯体配比不变的情况下,考察了前躯体中镉离子的浓度、pH及回流时间对CdTe生长的影响.并用透射电子显微镜(TEM),荧光分光光度计(FS),X射线衍射仪(XRD)等手段对制备的量子点进行了表征.结果表明:CdTe量子点的尺寸随回流时间而增长;反应的pH对量子点的荧光强度有显著影响;镉离子的浓度越大,量子点的生长速度越快,荧光强度却随之降低.     

一锅合成绿色到近红外发射的CdTe量子点

以3-巯基丙酸(MPA)为稳定剂,采用水相合成法制备了从绿色到近红外发射的CdTe量子点。系统研究了反应液pH值、镉和碲的物质的量之比及镉和3-巯基丙酸的物质的量之比等实验条件对CdTe量子点体系的发射波长和荧光量子产率的影响。在pH值为10.5,且nCd2+∶nTe2-∶nMPA=1∶0.05∶1.1的条件下,回流0.5 h,CdTe量子点体系在569 nm波长处的荧光量子产率达到30.8%;在7 h的回流时间内,制备的量子点的波长覆盖范围为525～730 nm。分别用X射线粉末衍射、透射电镜和红外光谱对CdTe量子点的晶体结构、形貌及表面基团进行表征。     

水热法快速合成绿色到近红外发光CdTe量子点

以3-巯基丙酸(MPA)和柠檬酸钠为稳定剂,Na2TeO3为碲源,利用水热法成功制备了从绿色到近红外发射的CdTe量子点,并详细探讨了影响CdTe量子点体系的荧光发射波长和量子产率的因素,如反应前驱液的pH值,反应物的浓度比和反应时间等实验条件.分别用X射线粉末衍射、透射电镜、紫外-可见光谱和荧光光谱对CdTe量子点进行了表征.     

表面修饰CdTe量子点的合成及其光学特性

在水相中合成高发光性能的CdTe量子点,研究以巯基乙酸(TGA)为稳定剂对CdTe表面进行修饰,制备在水中分散性良好的纳米晶,通过对CdTe量子点合成反应条件的摸索,掌握了其合成的反应规律.同时用紫外分光光度计、荧光分光光度计和透射电子显微镜对其进行了表征.结果表明,回流时间、n(Cd²⁺):n(HTe^-)、反应物浓度、TGA用量、反应体系pH值,对纳米晶的光学性质具有显著影响.回流2 h制得的CdTe纳米粒子直径约为5 nm,其发射峰窄且对称,表现出良好稳定的光学性质.     

微波和油浴加热下水溶性CdTe量子点的生长行为比较研究

应用X射线衍射(XRD)、透射电镜(TEM)、紫外吸收光谱(UV)和荧光光谱等表征技术观测微波和油浴两种不同加热方式下制备的量子点的晶型、形貌、分散性、生长速度和光学性能,研究了两种加热方式下水溶性CdTe量子点的生长速度变化和差异,并计算了相关动力学参数,考查了不同微波功率、不同配体、不同pH值等反应条件对量子点生长速度的影响。结果表明：微波加热可以提高量子点的尺寸分散性,但不能降低反应的活化能。两种加热方式所制备的量子点具有相同的形貌、晶型、生长速率及发光效率,量子点的生长速度不受微波功率的影响,而是强烈地依赖于配体的结构性质及溶液pH值。     

电化学法合成强荧光CdTe量子点

采用电化学方法产生的H2Te为碲源(Te2-),快速合成了水溶性强荧光的CdTe量子点.该方法具有操作简单、安全、快速廉价和可大量制备等优点.合成过程中考察了合成温度,pH值和配体比例对制备CdTe量子点的影响.在最优化的实验条件下,电化学方法合成的巯基丙酸配位的CdTe荧光量子产率可达到55％;通过紫外可见光谱(UV...     

谷胱甘肽稳定水溶性CdTe/ZnTe量子点的制备与表征

用还原型谷胱甘肽(GSH)作为稳定剂, 合成了水溶性的CdTe/ZnTe核壳结构的半导体量子点. 考察了Zn/Cd反应物配比及GSH用量对CdTe/ZnTe量子点的性能影响. 用高分辨透射电子显微镜(HRTEM)和X射线粉末衍射(XRD)光谱对CdTe和CdTe/ZnTe的形貌和晶体结构进行了表征. 荧光光谱结果表明, 核壳结构的CdTe/ZnTe量子点比单一的CdTe量子点具有更高的荧光量子产率和更好的光活化性能.     

水合肼还原二氧化碲水相合成CdTe量子点

以巯基乙酸为稳定剂, 氯化镉为镉源, 二氧化碲为碲源, 水合肼为还原剂, 一步合成了CdTe量子点. 研究了反应时间、 碲与镉的摩尔比及巯基乙酸与镉的摩尔比等实验条件对CdTe量子点生长过程的影响. 采用荧光光谱、 X射线粉末衍射和透射电子显微镜等对量子点的性能进行了表征. 结果表明, 反应时间及反应物的相对用量对量子点的生长和荧光光谱有明显影响, 所得CdTe量子点具有立方晶型, 发光颜色从绿色到红色连续可调, 荧光量子产率可达26%.     

颜色可调的高荧光CdTe量子点的水相合成

以亚碲酸钠为碲源,硼氢化钠为还原剂,一步合成了巯基丁二酸(MSA)稳定的CdTe量子点.研究了反应液pH值、镉与碲的摩尔比及镉与巯基丁二酸的摩尔比等实验条件对CdTe量子点体系荧光量子产率的影响,并用荧光光谱、X射线粉末衍射及透射电子显微镜等对其进行了表征.结果表明,CdTe量子点具有闪锌矿结构,形貌呈球状;在pH=1...     

Ultrafast synthesis of near-infrared-emitting aqueous CdTe/CdS quantum dots with high fluorescence

The traditional aqueous route to synthesis CdTe/CdS Core/shell (c/s) quantum dots (QDs) via decomposition of Cd-thiol complexes is usually time consuming. Herein, an ultrafast and facile aqueous synthetic approach under atmospheric pressure for CdTe/CdS c/s QDs with emission from the green to the near-infrared window (535–820 nm) is reported. With purified CdTe core QDs diluted in solution of Cd-3-mercaptopropionic acid (MPA) complexes, CdTe/CdS c/s QDs with emission wavelengths at 700 and 800 nm can be obtained within 20- and 45-min refluxing under the optimized experimental conditions, respectively. This is the most rapid way to prepare CdTe/CdS c/s QDs in aqueous phase, and the obtained QDs were highly luminescent without postsynthesis treatment. The influences of various experimental factors, including Cd²⁺ concentration, MPA-to-Cd ratio, pH value, and dilution ratio on the growth rate and luminescent properties of the obtained CdTe/CdS c/s QDs, have been taken into consideration. The three processes “purification-dilution-addition” ensure the synthesis environment with high pH value and low core concentration and have a marked impact on the rapid synthesis rate and the resulting high fluorescence of CdTe/CdS c/s QDs.     

Synthesis of CdTe Quantum Dots with Tunable Photoluminescence Using Tellurium Dioxide as Tellurium Source

A simple and convenient method has been developed for synthesis of water‐soluble CdTe quantum dots (QDs) under ambient atmospheric conditions. In contrast to the traditional aqueous synthesis, green to red emitting CdTe QDs were prepared by using TeO₂ to replace Te or Al₂Te₃ as tellurium source in this method. The influences of experimental variables, including pH value, 3‐mercaptopropionic acid (MPA)/Cd and Te/Cd molar ratios, on the emission peak and photoluminescence (PL) quantum yield (QY) of the obtained CdTe QDs have been systematically investigated. Experimental results indicate that green to red emitting CdTe QDs with a maximum photoluminescence quantum yield of 35.4% can be prepared at pH 11.3 and n_(Cd):n_(Te):n_(MPA)=1:0.1:1.7.     

One-pot synthesis of CdTe quantum dots using tellurium dioxide as a tellurium source in aqueous solution

A novel route has been developed for the synthesis of l-cysteine (Cys)-capped CdTe quantum dots (QDs) in an aqueous medium. Compared with previous reports, this synthesis was carried out in air atmosphere with one pot by using TeO₂ to replace Te or Al₂Te₃ as tellurium source. The mechanism for the formation of CdTe QDs is elucidated. The influences of various experimental variables on the luminescent properties of the obtained CdTe QDs have been systematically investigated, including refluxing time, pH value, Cd/Cys and Cd/Te molar ratios. Furthermore, the obtained QDs were characterized by Fourier transform infrared spectra, X-ray powder diffraction, and transmission electron microscopy, respectively. The results demonstrate that the obtained QDs have zincblende crystal structure with a sphere-like shape. Under the optimized experimental conditions, green- to yellow-emitting CdTe QDs with a maximum photoluminescence quantum yield of 14.6 % can be obtained.     

L-Cys/MPA共修饰CdTe量子点:制备、表征及其在细胞标记中的应用

以L-半胱氨酸(L-Cys)和巯基丙酸(MPA)为共修饰剂在水相中快速合成高质量CdTe量子点.通过紫外-可见分光光谱、荧光光谱、荧光寿命衰减曲线、透射电子显微图片、XRD图谱等相关方法对产物进行表征.调节L-Cys和MPA的摩尔比,对CdTe量子点的生长速率和光学特性有明显影响.结果证实:与单一修饰剂L-Cys或MPA相比,L-Cys/MPA共修饰CdTe量子点具有较快的荧光发射峰红移速率,且其粒径分布均一、稳定性强.50L-CdTe(L-Cys与MPA摩尔比为50%)的荧光量子产率达到66.4%,75L-CdTe(L-Cys与MPA摩尔比为75%)的荧光寿命为46.8 ns.细胞毒性实验证明75L-CdTe量子点对SiHa细胞毒性较小,细胞存活率为75%~95%.进一步将其用于标记细胞,表明75L-CdTe量子点能有效地对SiHa细胞进行荧光标记.L-Cys/MPA共修饰CdTe量子点具有良好的荧光特性和生物相容性,在生物医药领域具有重要的应用价值.     

Luminescent properties of water-soluble denatured bovine serum albumin-coated CdTe quantum dots

Chemically reduced bovine serum albumin (BSA) has been used to modify the surface of water-soluble CdTe quantum dots (QDs). It is demonstrated that the denatured BSA (dBSA) can be conjugated to the surface of CdTe QDs and thereby efficiently improve the chemical stability and the photoluminescence quantum yield (PL QY) of the QDs. It is inferred that a shell-like complex structure CdTe(x)(dBSA)(1-x) will form on the surface of the CdTe "core", resulting in the enhancement of PL intensity and the blue shift of the PL peak. This study of the effects of pH and dBSA concentration on optical properties of dBSA-coated QDs suggests that, at pH 6-9, the solution of dBSA-coated CdTe QDs can keep substantial stability and fluorescent brightness, whereas further increase of pH value leads to a dramatic decrease in PL QY and chemical stability. On the other hand, too high or too low initial dBSA concentration in the QD solution results in a decrease of PL QY for dBSA-coated CdTe QDs. This study provides a new approach of preparing stable water-soluble QDs with high PL QY and controllable luminescent colors for biological labeling applications.     

基于聚合物多齿配体的高性能CdTe量子点的微波水相合成

针对当前水相合成的量子点(QDs)光性能与稳定性等方面存在的不足,发展了基于聚合物多齿配体的水相制备策略.利用巯基修饰的聚丙烯酸(PAA-SH)作为多齿配体代替常用的巯基丙酸等单齿配体,结合微波辅助加热制备了CdTe量子点,研究了多齿配体对量子点的生长机制与荧光性能的影响.以PAA-SH为配体制备的CdTe量子点荧光性能优异(荧光量子效率(PLQY)可达75%),流体力学直径较小(~10 nm),稳定性也有明显提高.基于聚合物多齿配体的量子点制备技术有助于实现生物医学研究中急需的兼具高亮度、高稳定性、小尺寸等特征的高性能量子点生物探针的制备.