氮氯共掺杂石墨烯量子点的合成及其对汞离子检测

以果糖、乙二胺、盐酸为原料，采用水热法将N、Cl原子掺杂在石墨烯量子点上，制备出氮氯共掺杂石墨烯量子点(N,Cl-GQDs),利用透射电镜、X射线光电子能谱、紫外-可见吸收光谱、荧光光谱等手段对其结构和性能进行了表征。结果表明：合成的N,Cl-GQDs为分散效果良好的球形，与单独氮掺杂及未掺杂的石墨烯量子点相比，双元素掺杂石墨烯量子点具有更好的光学性能。同时利用电化学发光淬灭原理构建了传感器，实现了对汞离子的检测，计算得出检测限为0.03ng/mL。     

过渡金属离子(Mn、Cu、Fe)掺杂半导体纳米晶的研究进展

过渡金属掺杂量子点由于具有零自吸收、更宽的发射光谱范围、更好的光化学稳定性等优点,已经成为提高量子点光电性能的重要研究方向。本文首先简单介绍了其掺杂机制,发光原理,制备方法,然后着重介绍了Mn,Cu,Fe等过渡金属掺杂量子点的最新研究进展。通过对大量相关文献进行总结发现,量子点的量子效率以及发光特性主要受掺杂量子点的制备方法,掺杂浓度,壳层厚度等因素的影响,最后,分析了该领域中目前存在的问题,并提出了今后的研究方向。     

Cu掺杂ZnSe高效量子点的合成及其光学特性研究

采用生长掺杂方式制备了Cu掺杂ZnSe高效量子点, 探索了不同Zn、Se前驱体配比对ZnSe晶核以及ZnSe:Cu量子点质量的影响, 并研究了Cu离子掺杂过程中的光谱特征。研究表明, 进一步通过在表面掺杂的ZnSe:Cu量子点上同质包覆ZnSe壳层, 能够实现其发光效率和稳定性的有效提高; 采用配体交换能够实现ZnSe:Cu量子点由油溶性到水溶性的转变。这种新型的掺杂量子点有望替代传统含Cd量子点应用于环境友好型固体发光器件和生物标记。     

基于废弃火炬松木包装的碳量子点制备与性能

目的 为了改善废弃火炬松木材包装综合利用率低和功能化利用严重不足的现状,以其包装废弃物制备荧光碳量子点,实现高附加值利用。方法 首先,以废弃火炬松木材包装为碳源,以尿素和磷酸分别为氮、磷掺杂剂,采用水热法(温度为200 ℃、时间为12 h),制备氮磷掺杂碳量子点。接着,采用紫外可见光分光光度计、荧光分光光度计、透射电子显微镜、傅里叶红外光谱和X射线光电子能谱表征CQDs的物理结构、化学结构和光学性质,筛选出荧光强度高、荧光量子产率大的制备工艺。结果 所制备的氮磷掺杂火炬松荧光碳量子点呈规则的球形,其平均粒径为2.25 nm、粒径分布范围为1.3~3.4 nm,且在水溶液中分布均匀,无明显聚集;碳量子点表面具有丰富的醚键、碳碳双键以及含磷和含氮官能团;当火炬松木粉、去离子水、尿素、磷酸的质量比为1∶60∶0.5∶0.5时,所得荧光碳量子点的荧光最强、荧光量子产率最高,所得荧光量子产率比未掺杂碳量子点的提高了5.54倍。结论 以废弃火炬松木材包装为碳源制备荧光碳量子点的策略是可行的,可为火炬松木材包装废弃物的高值化和功能化利用提供了一条新的途径。     

Co2+掺杂水溶性ZnS量子点的制备及其光致发光性能

采用共沉淀法,以3-巯基丙酸为表面修饰剂,成功制备出Co2+掺杂水溶性ZnS量子点。采用X射线衍射仪、透射电子显微镜、原子发射光谱仪、紫外-可见吸收光谱仪和荧光分光光度计等,研究了Co2+掺杂剂及掺杂量对ZnS量子点的晶体结构、形貌和发光性能等的影响。结果表明:所得产物均为ZnS立方型闪锌矿结构,量子点呈不规则球形,粒径主要集中在5.2 nm左右;掺杂样品发红色荧光,发光性能明显增强,属于Co2+形成的杂质能级(4A1—4T1)与缺陷的复合发光。同时,利用红外吸收光谱对Co2+掺杂水溶性ZnS量子点的形成机理进行了初步探讨。     

绿色荧光碳量子点的细胞成像研究

以葡萄糖为碳源,采用一步超声法制备氮掺杂碳量子点,并进行海拉(Hela)细胞成像研究。所获得的氮掺杂碳量子点平均粒径3.3nm,并具有良好的水溶性、光致发光特性。氮掺杂碳量子点具有低细胞毒性,在氮掺杂碳量子点浓度为1mg/mL条件下,Hela细胞的存活率高于90%,在浓度高达5mg/mL条件下,Hela细胞的存活率仍高于60%。     

CdSe:X/ZnS掺杂型核壳量子点的化学合成及光谱性质研究

采用绿色合成工艺,通过在核壳量子点中掺杂不同的金属离子,在水溶液中合成了CdSe∶X/ZnS掺杂型核壳量子点。并利用多种分析测试手段对合成产物的结构以及光谱性质进行了详细地研究。XRD分析表明,核壳结构的量子点的衍射峰相对内层CdSe量子点向高角度方向移动,掺杂型核壳量子点的衍射峰较未掺杂量子点有向高角度移动趋势,合成量子点的平均晶粒尺寸约为2.3nm。SEM结果表明,合成的核壳量子点近似为球形。量子点的吸收峰与体材料相比,产生明显的蓝移,表现出明显的量子限域效应。样品具有很好的亲水性,在红外光线照射下出现丁达尔效应,样品的FT-IR结果表明配体MPA成功包覆在量子点的表面。     

新型氮掺杂碳点材料的合成及其光学性能

以β-环糊精为碳源,L-天冬氨酸为氮源,采用一步水热合成法制备了氮掺杂碳量子点(N-doped CDs),然后对N-doped CDs的组成、形貌、光学性质进行表征,并研究了不同氮掺杂含量和氧气对N-doped CDs光学性能的影响.研究结果表明,制备的N-doped CDs表面富含氧和氮元素,氮的掺杂能有效提高碳量子点的荧光强度,但是过多的氮掺杂会使其荧光量子产率下降.制备的N-doped CDs最大荧光量子产率为19.1％.此外,无氧环境中N-doped CDs的荧光强度大于有氧环境下的荧光强度,表明氧的存在对碳量子点材料表面荧光有猝灭作用.简便的制备方法和独特的光学特性使这些N-doped CDs材料在许多领域具有潜在的应用可能,例如白色发光二极管.     

Mn~(2+)掺杂水溶性ZnS量子点的制备及其光致发光性能

采用共沉淀法,在3-巯基丙酸(MPA)为表面修饰剂下,成功制备出Mn2+掺杂水溶性ZnS量子点。利用X射线衍射仪、透射电子显微镜、紫外-可见吸收光谱仪和荧光分光光度计等表征方法研究了Mn2+掺杂剂及掺杂量对ZnS量子点的晶体结构、形貌和发光性能等的影响。结果表明,所得产物为ZnS立方型闪锌矿结构,样品呈不规则球形,粒径主要集中在9.7nm左右;在320nm激发下,Mn2+掺杂ZnS量子点出现两个发射波峰,分别位于587和637nm处,其中587nm处的发射波峰为ZnS表面态缺陷发光,而637nm处的发射波峰则属于Mn2+∶4T1-6A1能级特征发光。同时,利用红外吸收光谱对Mn2+掺杂水溶性ZnS量子点的形成机理进行了初步探讨。     

樟子松基碳量子点的制备工艺优化

目的 将樟子松木材包装废弃物转化为荧光碳量子点,为实现废弃樟子松木材包装的高值化综合利用探索一条新途径。方法 以60目樟子松木材包装废弃物为碳量子点前驱体,分别以硫酸和乙二胺为硫和氮掺杂剂,在温度为200 ℃、时间为10 h的水热条件下合成樟子松基碳量子点。采用紫外可见光分光光度计、荧光分光光度计、透射电子显微镜、傅里叶红外光谱仪和X射线光电子能谱仪等表征手段,研究原材料配比对所制备樟子松基碳量子点物理结构、化学结构和光学性质的影响,并以碳量子点的荧光量子产率为评价指标,优化樟子松基碳量子点的制备工艺。结果 所得硫氮掺杂碳量子点呈规则球形,其平均粒径及粒径分布分别为4.30 nm和2.01~6.63 nm;当原材料配比为m(樟子松木粉)∶m(硫酸)∶m(乙二胺)=1∶1∶1时,合成的掺杂碳量子点的荧光最强、荧光量子产率最高。当樟子松木粉、去离子水、硫酸和乙二胺的质量比为1.250∶50∶1.250∶1.250时,掺杂碳量子点的荧光量子产率比未掺杂碳量子点的高约80倍。结论 将樟子松木材包装废弃物转化为荧光碳量子点,是实现废弃樟子松木材包装的高值化综合利用的新途径。     

Detection of bioconjugated quantum dots passivated with different ligands for bio-applications

Bioconjugation of quantum dots has resulted in a significant increase in resolution of biological fluorescent labeling. This intrinsic property of quantum dots can be utilized for sensitive detection of target analytes with high sensitivity; including pathogenic bacteria and cancer monitoring. The quantum dots and quantum dot doped silica nanoparticles exhibit prominent emission peaks when excited at 400 nm but on conjugation to model rabbit antigoat antibodies exhibit diminished intensity of emission peak at 600 nm. It shows that photoluminescence intensity of conjugated quantum dots and quantum dot doped silica nanoparticles could permit the detection of bioconjugation. Samples of conjugated and unconjugated quantum dots and quantum dot doped silica nanoparticles were subjected to enzyme linked immunosorbent assay for further confirmation of bioconjugation. In the present study ligand exchange, bioconjugation, fluorescence detection of bioconjugated quantum dots and quantum dot doped silica nanoparticles and further confirmation of bioconjugation by enzyme linked immunosorbent assay has been described.     

Mn‐doped ZnS quantum dots‐chlorin e6 shows potential as a treatment for chondrosarcoma: an in vitro study

Chondrosarcoma is the second‐most malignant cancer of the bone and routine treatments such as chemotherapy and radiotherapy have not responded to the treatment of this cancer. Due to the resistance of chondrosarcoma to radiotherapy, the combination of therapeutic methods has been considered in recent years. In this study, a novel combination approach is used that allows photodynamic therapy to be activated by X‐rays. The synthesis of Mn‐doped zinc sulphide (ZnS) quantum dots was carried out and chlorin e6 photosensitiser attached by covalent and non‐covalent methods and their application as an intracellular light source for photodynamic activation was investigated. The toxicity of each nanoparticles was evaluated on chondrosarcoma cancer cells (SW1353) before and after radiation. Also, the effect nanoparticle‐photosensitiser conjugated type was investigated in the therapeutic efficacy. The characterisation test (SEM, TEM, EDS, TGA, XRD and ICP analyses) was shown successful synthesis of Mn‐doped ZnS quantum dots. Chondrosarcoma cancer cell viability was significantly reduced when cells were treated with MPA‐capped Mn‐doped ZnS quantum dots‐chlorin e6 with spermine linker and with covalent attachment (P  ≤ 0.001). These results indicate that X‐ray can activate the quantum dot complexes for cancer treatment, which can be a novel method for treatment of chondrosarcoma.Inspec keywords: semiconductor quantum dots, X‐ray diffraction, transmission electron microscopy, cadmium compounds, cellular biophysics, drugs, manganese, biomedical materials, cancer, quantum dots, nanofabrication, ultraviolet spectra, zinc compounds, fluorescence, scanning electron microscopy, nanoparticles, nanomedicine, bone, photochemistry, photodynamic therapy, tumours, II‐VI semiconductors, laser applications in medicineOther keywords: noncovalent methods, photodynamic activation, chondrosarcoma cancer cells, chondrosarcoma cancer cell viability, quantum dot complexes, cancer treatment, malignant cancer, routine treatments, radiotherapy, therapeutic methods, Mn‐doped zinc sulphide quantum dots, in vitro study, MPA‐capped Mn‐doped ZnS quantum dots‐chlorin e6, nanoparticle‐photosensitiser conjugated type, ZnS, Mn, ZnS:Mn     

Self-aligned charge read-out for InAs nanowire quantum dots

A highly sensitive charge detector is realized for a quantum dot in an InAs nanowire. We have developed a self-aligned etching process to fabricate in a single step a quantum point contact in a two-dimensional electron gas and a quantum dot in an InAs nanowire. The quantum dot is strongly coupled to the underlying point contact that is used as a charge detector. The addition of one electron to the quantum dot leads to a change of the conductance of the charge detector by typically 20%. The charge sensitivity of the detector is used to measure Coulomb diamonds as well as charging events outside the dot. Charge stability diagrams measured by transport through the quantum dot and charge detection merge perfectly.     

异质外延自组织量子点弹性应变场分布的研究

通过有限元法,在ANSYS环境下,利用二维模型对自组织应变外延异质结透镜形量子点的应力应变分布情况进行了系统分析。分析过程分别考虑了孤立量子点系统、单层多量子点系统以及量子点超晶格系统3种情况,结果表明单层和超晶格多量子点系统衬底之间存在的长程相互作用力对量子点及其周围的应力应变分布有显著影响。在计算应变对多量子点系统的电子结构的影响时,必须将多量子点系统整体考虑。     

异质外延自组织锥形量子点长程相互作用对弹性应变场分布的影响

利用有限元法,在ANSYS 环境下,利用二维模型对自组织应变外延异质结锥形量子点的应力应变分布情况进行了系统分析.分析过程分别考虑了孤立锥形量子点系统、单层多量子点系统以及量子点超晶格系统三种情况,结果表明,单层和超晶格多量子点系统衬底之间存在的长程相互作用力对量子点及其周围的应力应变分布有显著影响.在计算应变对多量子点系统的电子结构的影响时,必须将多量子点之间的相互作用对应变的贡献考虑进去.     

量子点太阳电池的探索

阐述了探索量子点太阳电池的重要意义与物理构想,简要介绍了两种不同结构组态的量子点太阳电池的光伏性能,如p-i-n量子点太阳电池和量子点敏化太阳电池.对发生在各种量子点(PbSe、PbS、PbTe、CdSe和Si)中的因碰撞电离而导致的多激子产生效应及其研究进展进行了重点评述,并提出了设计与制作量子点太阳电池的若干技术对策.可以预期,具有超高能量转换效率、低制作成本与高可靠性的量子点太阳电池的实现,有可能对未来的光伏技术与产业产生革命性的影响.     

Quantitative excited state spectroscopy of a single InGaAs quantum dot molecule through multi-million-atom electronic structure calculations

Atomistic electronic structure calculations are performed to study the coherent inter-dot couplings of the electronic states in a single InGaAs quantum dot molecule. The experimentally observed excitonic spectrum by Krenner et al (2005) Phys. Rev. Lett. 94 057402 is quantitatively reproduced, and the correct energy states are identified based on a previously validated atomistic tight binding model. The extended devices are represented explicitly in space with 15-million-atom structures. An excited state spectroscopy technique is applied where the externally applied electric field is swept to probe the ladder of the electronic energy levels (electron or hole) of one quantum dot through anti-crossings with the energy levels of the other quantum dot in a two-quantum-dot molecule. This technique can be used to estimate the spatial electron-hole spacing inside the quantum dot molecule as well as to reverse engineer quantum dot geometry parameters such as the quantum dot separation. Crystal-deformation-induced piezoelectric effects have been discussed in the literature as minor perturbations lifting degeneracies of the electron excited (P and D) states, thus affecting polarization alignment of wavefunction lobes for III-V heterostructures such as single InAs/GaAs quantum dots. In contrast, this work demonstrates the crucial importance of piezoelectricity to resolve the symmetries and energies of the excited states through matching the experimentally measured spectrum in an InGaAs quantum dot molecule under the influence of an electric field. Both linear and quadratic piezoelectric effects are studied for the first time for a quantum dot molecule and demonstrated to be indeed important. The net piezoelectric contribution is found to be critical in determining the correct energy spectrum, which is in contrast to recent studies reporting vanishing net piezoelectric contributions.     

量子点材料应用于发光二极管的研究进展

量子点材料因具有独特的光学特性而被广泛应用于发光领域,用其作发光层可制成量子点发光二极管。与有机电致发光二极管相比,量子点发光二极管具有发光光谱窄、色域广、稳定性好、寿命长、制作成本低等优势。本文介绍了量子点发光器件在国内外的热点研究方向及取得的成果,并对其发展前景进行展望。     

Intersublevel Spectroscopy on Single InAs-Quantum Dots by Terahertz Near-Field Microscopy

Using scattering-type near-field infrared microscopy in combination with a free-electron laser, intersublevel transitions in buried single InAs quantum dots are investigated. The experiments are performed at room temperature on doped self-assembled quantum dots capped with a 70 nm GaAs layer. Clear near-field contrast of single dots is observed when the photon energy of the incident beam matches intersublevel transition energies, namely the p-d and s-d transition of conduction band electrons confined in the dots. The observed room-temperature line width of 5-8 meV of these resonances in the mid-infrared range is significantly below the inhomogeneously broadened spectral lines of quantum dot ensembles. The experiment highlights the strength of near-field microspectroscopy by demonstrating signals from bound-to-bound transitions of single electrons in a probe volume of the order of (100 nm)(3).     

The influence of post-growth annealing on the optical properties of InAs quantum dot chains grown on pre-patterned GaAs(100)

We report on the effect of post-growth thermal annealing of [011]- ,[011(-)]-, and [010]-oriented quantum dot chains grown by molecular beam epitaxy on GaAs(100) substrates patterned by UV-nanoimprint lithography. We show that the quantum dot chains experience a blueshift of the photoluminescence energy, spectral narrowing, and a reduction of the intersubband energy separation during annealing. The photoluminescence blueshift is more rapid for the quantum dot chains than for self-assembled quantum dots that were used as a reference. Furthermore, we studied polarization resolved photoluminescence and observed that annealing reduces the intrinsic optical anisotropy of the quantum dot chains and the self-assembled quantum dots.