CdTe,核 壳型CdTe/CdS及CdTe/ZnS量子点的合成及表征

在水相中制备了半导体CdTe纳米晶,核 壳型CdTe/CdS和CdTe/ZnS纳米晶（即量子点;QDs）.利用扫描隧道显微镜（STM）和荧光光谱(FS)对合成的纳米晶量子点进行了研究,并且根据FS的数据进行了量子效率的计算.STM的结果表明合成的量子点直径约为3 nm并且分布良好.为了提高量子效率,对Cd2+浓度和Cd2+∶S2－比例等反应条件进行了研究,结果表明随着回流时间的增加,核 壳型量子点CdTe/CdS的量子效率总体上呈下降趋势.CdTe/CdS在pH8.5,Cd2+∶S2－=10∶1（摩尔比）时可获得80.0%的最大量子效率.同时制备了核 壳型量子点CdTe/ZnS,其最大发射波长由551 nm（CdTe）红移到635 nm（CdTe/ZnS）表明量子点的尺寸在增长,但是量子效率下降到14.4%. 当前研究的量子点可适用于生物标记,生物成像,以及基于共振能量转移的生物传感研究.     

氮掺杂发光碳纳米点的研究探索

采用微波法制备了氮掺杂碳纳米点。通过调控碳纳米点中氮元素的掺杂含量和表面的化学环境,实现了对碳纳米点发光特性的调控。在此基础上,可实现完全基于氮掺杂碳纳米点的荧光墨水、比率型荧光探针及光泵浦激光。研究目的在于探索氮掺杂碳纳米点的发光机理,揭示影响碳纳米点荧光量子效率的因素及其在生物成像、传感、防伪、信息存储、激光等领域的应用。     

基于氮掺杂碳量子点/DNA自组装纳米探针检测鱼精蛋白

将柠檬酸置于单乙醇胺中,通过简单加热实现快速、大规模的合成氮掺杂荧光碳点。所得氮掺杂碳量子点被370 nm 的光激发后在458 nm 处有较强的荧光发射,最大吸收波长为365.085 nm。脱氧核糖核苷酸能增强该碳量子点的荧光且具有相关线性关系,因而制备了氮掺杂碳点与脱氧核糖核苷酸的杂交纳米复合物（纳米探针）,并首次用于检测鱼精蛋白。在实验条件最佳情况下,该方法简便、选择性好,该分析方法的线性检测范围为1~10 μg·mL^-1,检出限可达0.61 μg·mL^-1。     

ZnS∶Cu-罗丹明B的荧光共振能量转移性质

为了解决现有的基于量子点荧光共振能量转移体系的生物毒性问题,选用无毒的ZnS∶Cu量子点与罗丹明B构建新型荧光共振能量转移体系。通过共沉淀法成功制备了形貌均一的ZnS∶Cu纳米晶量子点。在此基础上,测试了不同掺杂浓度的ZnS∶Cu量子点及罗丹明B的荧光光谱。然后,通过对ZnS∶Cu量子点的表面修饰构建了以ZnS∶Cu量子点为供体、罗丹明B为受体的荧光共振能量转移体系。实验结果表明:ZnS∶2%Cu量子点的发光光谱与罗丹明B的吸收光谱在481 nm处有较大重合,说明构建荧光共振能量转移的最佳铜掺杂摩尔分数为2%。通过计算发现以ZnS∶2%Cu量子点为供体、罗丹明B为受体的荧光共振能量转移体系的能量转移效率为25.8%。进一步实验结果表明,罗丹明B浓度也能够影响能量转移。     

柿子叶制备碳量子点的光谱性质及对Fe3+的荧光探针

碳量子点作为碳纳米材料中的新成员,具有较高的光学稳定性、低毒性、良好水溶性、原料来源广泛、制备方法多样等多种优点,在分析检测、生物标记、光催化降解以及环境监测等领域具有广泛的应用前景, 对碳量子点的研究引起了国内外学者极大兴趣。水中Fe3+含量的超标会对生活饮用和工业生产造成一定的危害,所以准确快速地检测水中Fe3+的含量,对人体健康具有重要的意义。目前,对Fe3+进行检测的方法有伏安法、荧光光谱法、电化学法以及火焰原子吸收光谱法等,其中荧光光谱法具有快速响应和方法简便的特点,比其他方法更有优势。以柿子叶为碳源,采用水热法制备了发蓝绿色荧光的碳量子点,通过X射线衍射、高分辨透射电子显微镜、傅里叶变换红外光谱、紫外-可见吸收光谱及荧光光谱等技术对碳量子点的结构、微观形态和光谱学性质进行了详细表征。柿子叶制备的碳量子点呈现为分散均匀的球形颗粒,颗粒平均直径大约5.9 nm,碳量子点颗粒表面具有丰富的含氧官能团,在277 nm有明显的紫外吸收,可归因于C═O的n→π*跃迁。碳量子点的发射波长和荧光强度具有明显的激发依赖性,在410 nm光激发下,发射波长峰值为498 nm且荧光峰最强,荧光寿命为4.59 ns。采用多种金属离子对柿子叶制备的碳量子点在荧光传感方面进行了探究,分析发现该碳量子点对金属Fe3+具有极高的选择性,可作为荧光探针检测水中微量的Fe3+含量,其荧光猝灭率F₀/F与金属Fe3+浓度在1~120 μmol·L-1范围内呈现良好的线性关系（R2 = 0.992）,猝灭常数和最低检出限分别为8.84×103 L·mol-1和0.21 μmol·L-1,最低检出限数值明显小于最近一些文献的报导结果。该工作提供了一种原料天然、操作简单、成本低廉的制备工艺,开发了荧光检测水中微量金属铁离子的新方法。     

基于表面等离子体共振效应的荧光太阳集光器制备及其性能

金属纳米颗粒的表面等离子体共振效应能够对特定波长入射光的吸收或者散射增强,正因为其独特的光学性质,金属纳米颗粒被尝试应用于荧光太阳集光器.本文利用全无机钙钛矿CsPbBr3量子点、Au纳米颗粒和硫醇-烯聚合物制备荧光太阳集光器.研究发现,掺杂适量Au纳米颗粒可以通过表面等离子体共振效应提高全无机钙钛矿CsPbBr3量子...     

较高掺杂浓度下CdSe/ZnS量子点光纤光致荧光光谱

制备了一种较高浓度掺杂的CdSe/ZnS量子点掺杂光纤.测量了不同掺杂浓度和不同光纤长度下的量子点光纤光致荧光光谱,得剑了荧光峰值增益最大时的量子点掺杂浓度和光纤长度.与低浓度掺杂光纤相比,较高掺杂浓度光纤中的荧光峰值光强明显提高.荧光峰值光强随光纤长度的变化在短距离内(L<1 cm)急剧上升,之后缓慢均匀下降.波长473 nm激励光强随光纤}乏度的变化呈指数形式衰减,消光系数为0.26～1.02 cm-1.在给定激励光强和激励波长的条件下,光纤中可达到最大荧光辐射的晕子点总数为一恒量.光纤中的荧光峰值波长存在红移,红移大小约8～15 nm,红移量与掺杂浓度以及光纤长度有关.这些实验结果可为今后量子点光纤放大器的研制提供参考.     

红、绿CdSe@ZnS量子点配比对三波段标准白光LED器件的影响

将一步法合成的具有梯度合金结构的红光、绿光CdSe@ZnS量子点与硅胶均匀混合后,作为光转换层涂覆到蓝色InGaN LED芯片上,制备了不含荧光材料的三波段白光LED器件。研究了峰值为650 nm和550 nm的高效率红、绿量子点在硅胶中的含量及配比对白光LED色坐标以及效率的影响。结果表明,当红、绿量子点配比为2：3时,可得到发射纯正白光的QDs-LED器件,色坐标为（0.322 8,0.335 9）、色温为5 725 K,功率效率为26.61 lm/W,显色指数为72.7。光谱中红、蓝、绿三色发光峰的半高宽分别为30,25,38 nm,表明器件具有很好的单色性和高色纯度。     

SiO2纳米颗粒对R6G-乙醇溶液荧光光谱影响

在3×10－4M和1×10－4M浓度的R6G-乙醇溶液中分别掺杂了8个不同浓度的SiO2纳米颗粒（107～1012 个/mL）.研究了SiO2纳米颗粒（100 nm）对若丹明6G（R6G）荧光光谱的影响,结果表明:n1～n4(1012～1010个/mL)浓度掺杂的SiO2纳米颗粒在549 nm处的有很好的荧光增强作用,对570 nm处的荧光峰有明显的粹灭作用|n5～n8(109~107个/mL)浓度掺杂的SiO2纳米颗粒在549 nm处没有明显的荧光增强作用,但对570 nm处的荧光峰有增强作用,荧光增强因子可达10%~20%.荧光增强与粹灭的原因在于纳米颗粒对荧光的散射作用和R6G无荧光H-型二聚体或荧光J-型二聚体的形成.     

一步合成硫、氮共掺杂的碳量子点及其在Fe~(3+)检测中的应用

碳量子点的光致发光性质不仅决定于尺寸还依赖于它的表面态,因此通过在碳量子点表面掺杂或嫁接不同元素与基团有望调节它的荧光发射行为。为了研究多种元素掺杂对碳量子点发光性质的影响,本文以对氨基苯磺酸为原料,通过水热法一步合成了氮、硫共掺杂的碳量子点。实验结果表明:制备的碳量子点尺寸分布均匀,氮、硫分别以氨基和磺酸基团的形式存在于碳量子点的表面。与已有的报道不同,碳量子点展现出了非激发波长依赖的蓝光发射行为,三价铁离子可有效猝灭其荧光,铁离子浓度在0~10-3mol·L-1范围内与碳量子点的荧光猝灭程度呈现良好的线性关系,检出限约为10-7mol·L-1。制备的碳量子点对三价铁离子具有高选择性、高灵敏性以及较好的抗干扰能力,能作为三价铁离子检测的传感器。     

Study of the Optical Properties of CdZnSe/ZnS-Quantum Dot–Au-Nanoparticle Complexes

The interaction of gold nanoparticles (NPs) and semiconductor alloyed CdZnSe/ZnS quantum dots (QDs) in colloidal solutions is studied. It is shown that the photoluminescence intensity of QDs in a mixture decreases compared to that in the initial QD solution, which is caused by resonance nonradiative energy transfer from QDs to Au NPs in spontaneously formed aggregates. To control the formation of pairs of interacting QDs and Au NPs, we proposed have a method for creating QD–Au NP complexes bound by special molecules—ligands. It is shown that the morphology and optical properties of the samples obtained depend on the method of their preparation, in particular, on the chemical environment of QDs. It is found that the complexes form in the case of addition of hydrophilic Au NPs to hydrophobic QDs and that this almost does not change the optical properties of the latter compared to those of quasi-isolated QDs in colloidal solution.     

Near‐field optical enhancement by lead‐sulfide quantum dots and metallic nanoparticles for SERS

There is a growing interest in using quantum dots (QDs) and metallic nanoparticles (NPs), both for luminescence enhancement and surface‐enhanced Raman scattering (SERS). Here, we study the electromagnetic‐field enhancement that can be generated by lead‐sulfide (PbS) QDs using three‐dimensional finite‐element simulations. We investigate the field enhancement associated with combinations of PbS QDs with metallic NPs and substrates. The results show that high field enhancement can be achieved by combining PbS QDs with metallic NPs of larger sizes. The ideal size for Ag NPs is 25 nm, providing a SERS enhancement factor of ~5*10⁸ for light polarization parallel to the NP dimer axis and a gap of 0.6 nm. For Au NPs, the bigger the size, the higher is the field for the studied diameters, up to 50 nm. The near‐field values for PbS QDs above metallic substrates were found to be lower compared to the case of PbS QD‐metal NP dimers. This study provides the understanding for the design and application of QDs for the enhancement of near‐field phenomena. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental investigation of energy transfer between CdSe/ZnS quantum dots and different-sized gold nanoparticles

Hybrid nanostructures of quantum dots(QDs) and metallic nanostructure are attractive for future use in a variety of optoelectronic devices. For photodetection applications, it is important that the photoluminescence (PL) of QDs is quenched by the metallic nanostructures. Here, the quenching efficiency of CdSe/ZnS core-shell quantum dots (QDs) with different sized gold nanoparticles (NPs) films through energy transfer is investigated by measuring the PL intensity of the hybrid nanostructures. In our research, the gold NPs films are formed by the post-annealing of the deposited Au films on the quartz substrate. We find that the energy transfer from the QDs to the Au NPs strongly depends on the sizes of the Au NPs. For CdSe/ZnS QDs direct contact with the Au NPs films, the largest energy transfer efficiency are detected when the resonance absorption peak of the Au NPs is nearest to the emission peak of the CdSe/ZnS QDs. However, when there is a PMMA spacer between the QDs layer and the Au NPs films, firstly, we find that the energy transfer efficiency is weakened, and the largest energy transfer efficiency is obtained when the resonant absorption peak of the Au NPs is farthest to the emission peak wavelength of CdSe/ZnS QDs. These results will be useful for the potential design of the high efficiency QDs optoelectronic devices.     

Au纳米颗粒和CdTe量子点复合体系发光增强和猝灭效应

利用金属蒸发真空多弧离子源注入机, 将Au离子注入到高纯石英玻璃来制备镶嵌有Au 纳米颗粒的衬底材料, 随后将化学方法合成的CdTe量子点旋涂在玻璃衬底上制备了Au纳米颗粒和CdTe量子点复合体系. 通过对镶嵌有Au纳米颗粒的衬底进行热退火处理来控制Au纳米颗粒的生长和分布, 系统研究了Au纳米颗粒的局域表面等离子体共振对CdTe量子点光致发光性能的影响. 利用光学吸收谱、原子力显微镜、透射电子显微镜和光致发光谱对样品进行了表征和测试. 光致发光谱表明, Au纳米颗粒的局域表面等离子体对CdTe量子点的发光有增强效应也有猝灭效应. 深入分析了Au纳米颗粒和CdTe量子点之间的相互作用过程, 提出了关于Au-CdTe 纳米复合体系中CdTe 发光增强和猝灭的新机理. 该实验结果为利用金属纳米颗粒表面等离子体技术制备高发光性能的光电子器件提供了较好的参考.     

应用量子点探针观察粒子辐射细胞损伤动态过程

荧光量子点由于具有发射荧光效率高、光稳定性好、无光漂白等优良特性,因此在生物学研究中得到广泛应用。用量子点标记细胞,通过量子点荧光可以对细胞进行长时程观察,实现活细胞动态示踪。利用量子点和DiO荧光染料对A549细胞膜双染,直观展示了量子点优于有机荧光染料的抗光漂白特性,并阐述了一种利用量子点对细胞A549进行标记并观测在α粒子辐照下细胞损伤动态变化过程的方法,这种方法对于阐明粒子辐射作用细胞的过程、了解辐射损伤的机理有一定的优势。     

PbSe量子点荧光匹配气体吸收光谱方法研究

PbSe量子点(PbSe-QDs)是红外波段的典型纳米材料,其具有大的玻尔半径、小的体材料禁带宽度(玻尔半径是46 nm,体材料禁带宽度是0.28 eV),因此,在近红外区域,PbSe-QDs具有强大的尺寸受限效应和较高的量子产出率。本文对不同尺寸的PbSe量子点的荧光光谱特性进行了研究,提出了一种通过调节PbSe量子点的量子尺寸匹配气体吸收光谱的方法。采用配位溶剂的方法制备了尺寸为4.6和6.1 nm的PbSe量子点,将该PbSe量子点沉积到GaN发光芯片上并经过紫外光照处理和固化后制成了光致发光的近红外光源,其中4.6 nm的PbSe-QDs的沉积厚度为671.5 μm,而6.1 nm的PbSe-QDs的沉积厚度为48 μm。将制成的近红外光源应用到C₂H₂气体和NH₃气体的检测实验中,实验结果表明,通过改变PbSe量子点的尺寸可以调节光源光致发光峰的位置,从而覆盖目标气体在近红外波段的吸收谱线。4.6 nm的光源发射光谱包含了1 500～1 550 nm之间的C₂H₂气体的全部的吸收谱;6.1 nm的光源发射光谱包含了1 900～2 060 nm之间的NH₃气体的全部的吸收谱。这种利用PbSe量子点尺寸的可调性匹配对应气体吸收谱的方法是可行和有效的,具有广阔的应用前景。     

The influence of the quantum dot/polymethylmethacrylate composite preparation method on the stability of its optical properties under laser radiation

Photoluminescent semiconductor nanocrystals, quantum dots (QDs), are nowadays one of the most promising materials for developing a new generation of fluorescent labels, new types of light-emitting devices and displays, flexible electronic components, and solar panels. In many areas the use of QDs is associated with an intense optical excitation, which, in the case of a prolonged exposure, often leads to changes in their optical characteristics. In the present work we examined how the method of preparation of quantum dot/polymethylmethacrylate (QD/PMMA) composite influenced the stability of the optical properties of QD inside the polymer matrix under irradiation by different laser harmonics in the UV (355 nm) and visible (532 nm) spectral regions. The composites were synthesized by spin-coating and radical polymerization methods. Experiments with the samples obtained by spin-coating showed that the properties of the QD/PMMA films remain almost constant at values of the radiation dose below ~10 fJ per particle. Irradiating the composites prepared by the radical polymerization method, we observed a monotonic increase in the luminescence quantum yield (QY) accompanied by an increase in the luminescence decay time regardless of the wavelength of the incident radiation. We assume that the observed difference in the optical properties of the samples under exposure to laser radiation is associated with the processes occurring during radical polymerization, in particular, with charge transfer from the radical particles inside QDs. The results of this study are important for understanding photophysical properties of composites on the basis of QDs, as well as for selection of the type of polymer and the composite synthesis method with quantum dots that would allow one to avoid the degradation of their luminescence.     

以巯基丙酸为稳定剂的水溶性CdTe量子点的水热合成及表征

以巯基丙酸(MPA)为稳定剂,采用水热合成方法在160 ℃下合成水溶性CdTe量子点。研究了不同反应时间及反应前驱体溶液的不同pH值对合成的CdTe量子点光学性质的影响。结果表明:所制得的CdTe量子点的荧光发射波长在510~661 nm范围内连续可调,并且CdTe量子点的光学性质强烈地依赖于反应前驱体溶液的pH值,最佳pH值为9。透射电子显微镜和X射线衍射分析表明所制备的CdTe量子点的形状接近于球形,粒径分布较均匀。与回流方法制备的水溶性量子点相比,高温条件下的水热合成方法简单,反应时间短,CdTe量子点生长速度快,100 min就可生长到3.5 nm,并且所制得的CdTe量子点荧光强度高,稳定性好,荧光量子产率也较高,最高可达44.6%。     

Preparation of Highly Biocompatible ZnSe Quantum Dots Using a New Source of Acetyl Cysteine as Capping Agent

In this paper, we describe a facile method for preparation of ZnSe quantum dots (QDs) using an inexpensive and biocompatible source of acetyl cysteine in aqueous media. The structural properties of the ZnSe QDs have been characterized using XRD, FT-IR, and TEM techniques. The optical properties of the as-prepared QDs were found to be size-dependent, due to the strong confinement regime at relatively low refluxing time. Effect of solution pH and refluxing temperature on absorption and emission characteristics of the ZnSe QDs was studied. The empirical effective mass approximation also reveals that, both solution pH and refluxing temperature parameters would effect on ZnSe QDs growth, and increase their size. However, the influence of the solution pH was found to be more prominent. Water-solubility, high emission intensity and sub-10 nm nanocrystals size are the most essential features that suggest our synthesized aqueous-based ZnSe QDs (with a very cost-effective and biocompatible capping agent) can be utilized for biological intentions.     

硒化镉发光量子点的制备及其在有机发光器件中的应用

硒化镉量子点具有随粒径尺寸改变,而产生发光波长调变的特性,目前已被广泛研究。本研究是由化学溶胶法合成不同粒径尺寸的核壳型CdSe／ZnS硒化镉量子点,其表面包覆十六烷基胺,避免分子团聚现象。在由硒化镉成核温度的控制,成功地制备一系列具有各种尺寸粒径的核壳型硒化镉量子点(2—6nm)。本研究也合成了含有纳米金粒子于核壳型硒化镉量子点,实验结果发现：硒化镉发光效率明显的提高。在有机发光器件的应用方面,将发光波长为505nm核壳型CdSe／ZnS量子点掺入溶有发光波长为570nm铱化合物的氯仿溶液时,其溶液的光致发光光谱表明,原量子点的发光特性消失,只有铱化合物的发光依然存在,且其发光强度呈现明显增强趋势,我们推测此现象源自于量子点到铱化合物能量转移的机制。我们也以含有核壳型硒化镉量子点的铱化合物与PVK混合材料为发光层,成功的制作发光二极管器件,器件的发光效率因核壳型硒化镉的掺杂,明显提高2倍多。