Photocatalytic technology is an effective way to solve the two major problems of environmental problems and energy crisis. The development of efficient photocatalysts has become a research hotspot in this field. As new type of carbon nanomaterial, Carbon quantum dots (CQDs) have garnered much attention in the field of photocatalysis because of their unique up-conversion luminescence and excellent photogenerated electron transfer properties. In this paper, the mechanism of photocatalytic degradation of pollutants and the properties of carbon quantum dots was introduced, the research progress of photocatalytic degradation of organic pollutants in water by carbon quantum dots was reviewed with emphasis, followed by an outlook on their future and potential development.

ZnO quantum dots with different Eu-doped concentrations (0, 0.05, 0.10 and 0.15 mol/L) were prepared based on hydrothermal and spin-coating methods. Photoanode films were prepared on the basis of Eu-doped ZnO quantum dots, and quantum dot sensitized solar cells were prepared as photoanodes. The effects of Eu-doped concentration on the morphology, crystal structure, spectral properties and photoelectric properties of ZnO films were studied. The results showed that Eu-doped ZnO nanorods prepared by hydrothermal method belong to hexagonal wurtzite structure. Eu-doped ZnO nanorods did not produce new products, but refined the diameter of ZnO nanorod array, with a diameter distribution of 45~60 nm and a height of about 1.2 μm. The orientation and uniformity of ZnO nanorods had been improved. Eu doping reduced the band gap width of ZnO, reduced the photoluminescence intensity of ZnO, and improved the separation ability of electron pairs. When the concentration of Eu doping was 0.10 mol/L, the minimum band gap width of ZnO was 3.09, and the photoluminescence intensity was the lowest. The doping of Eu improved the photoelectric performance of the quantum dot sensitized solar cell assembled based on ZnO as the counter electrode. When the concentration of Eu doping was 0.10 mol/L, the photoelectric conversion efficiency could reach 4.03%, the charge transfer impedance of the counter electrode was 1.38 Ω, the exchange current density of the counter electrode was 9.92 mA/cm², and the photoelectric performance was the best.

Carbon quantum dots (CDs) are widely used in various fields due to their unique physical or chemical properties. Compared with traditional semiconductor quantum dots, the biggest advantages of CDs are low cytotoxicity, high biocompatibility, and at the same time being environmentally friendly. Obtaining carbon dots that meet the application conditions by selecting a specific synthesis or modification method is an urgent need for researchers. This paper reviews various top-down and bottom-up synthesis methods of CDs and describes their various properties after synthesis, in which the top-down method is biased towards producing a larger amount of Cdots, but the size and Cdots form is difficult to control. The bottom-up method can better control the size and shape of carbon dots, but the process is more complicated and time-consuming. The research progress of surface modification of CDs, including surface passivation and surface functionalization, was further discussed. Moreover, the characteristics of Cdots prepared by different synthesis methods or modification methods are quite different, extending their applications in various aspects, including cell imaging, fluorescence sensing, drug delivery, photocatalysis, ion detection, etc. Finally, we summarize and analyze the aspects of carbon dots that can be further explored, in order to provide references for more in-depth research and wider application of carbon dots.

In recent years, due to the rapid development of economy, a large number of pollutants have been produced, causing extremely serious harm to the environment. Among them, waste water has affected human life and health through various channels, but has not been effectively solved. Carbon quantum dots (CQDs), as a new type of nanocarbon materials with unique fluorescence properties, have the characteristics of low cost and environmental friendliness, among which the low toxicity and fluorescence characteristics can be used in the field of wastewater treatment. Therefore, this paper first introduces the common preparation methods of carbon quantum dots, and summarizes their advantages and disadvantages. Secondly, the latest application of carbon quantum dots as a catalyst for the degradation of various pollutants in wastewater, the preparation of composite film for the adsorption of heavy metals and organic dyes in wastewater, and as a sensor for the monitoring of toxic ions in wastewater are introduced. Finally, the shortcomings of carbon quantum dots in wastewater treatment are summarized, and the opportunities and challenges that carbon quantum dots will face in the future are proposed.

Chiral carbon quantum dots have a wide application prospect in sensors, catalysis and biomedicine due to their excellent properties. They not only have chiral properties, but also inherit the excellent properties of carbon quantum dots including optical activity, photoluminescence, low toxicity and good biocompatibility. In this paper, it is summarized on the development process, the synthesis methods, and application research of chiral carbon quantum dots. And the prospect of the chiral carbon quantum dots are also prospected. It will provide reference for the related application research of chiral carbon dots in the future.

Silver based nanomaterials have excellent bactericidal potential and can be used as antibacterial agents. Therefore, it is of great significance to synthesize silver sulfide nanomaterials by a simple, environmentally friendly and economical method. In this paper, silver sulfide quantum dots are biosynthesized using silver nitrate and sodium sulfite as precursors, and their possible antibacterial properties are revealed. Meyerozyma sp., a heavy metal tolerant fungus screened from soil of Daqing Oilfield, is used. Silver sulfide (Ag₂S) quantum dots are biosynthesized by reducing silver nitrate and sodium sulfite. The synthesized silver sulfide (Ag₂S) quantum dots are characterized by UV-vis, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), inverted fluorescence microscope and scanning electron microscope (SEM). The antibacterial activity of silver sulfide (Ag₂S) quantum dots is studied by disk diffusion method and drop plate sterilization. The results show that the silver sulfide (Ag₂S) quantum dots synthesized by Meyerozyma sp. are monoclinic α -Ag₂S crystals with the highest absorption peak at 410 nm. With the increase of the concentration of silver sulfide quantum, the diameter of the inhibition zone increases, and the antibacterial activity against gram-negative bacteria and gram-positive bacteria increases. The inhibition rate of silver sulfide (Ag₂S) quantum dots against Pseudomonas aeruginosa and Escherichia coli reaches 100% at 30 min and 90 min respectively. The inhibition rate of bacillus was 99.9% within 2 h. The possible antibacterial mechanism of silver sulfide (Ag₂S) quantum dots against bacteria is analyzed by SEM. The results show that silver sulfide (Ag₂S) quantum dots inhibit and damage the cell surface of Gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa and Gram-positive bacillus, and show significant antibacterial activity, which may be due to the small particle size of silver sulfide (Ag₂S) quantum dots. It attaches to the surface of the cell membrane of bacteria, causing damage to the cell membrane, and penetrates the cell membrane, destroying the DNA and proteins therein and leading to cell death.

With the aging of population and increasing in life expectancy, the incidence/mortality rate of cancer in our country has ranked first in the world. Although many therapy strategies have been proposed, such as photothermal therapy, immunotherapy, etc., chemotherapy is still the first choice for cancer treatment. However, severe side effects greatly limit the efficacy of chemotherapy. To solve this problem, people use nanocarriers to deliver chemotherapeutic drugs. Among all kinds of nanocarriers, non-heavy metal quantum dots (NHM-QDs) have attracted much attention in biomedicine field due to their special physical and chemical properties, such as easily-modified surface structures, high surface area and low toxicity. Here, we present a review of current development in non-heavy metal quantum dots, especially their applications for drug delivery, including carbon quantum dots (CQDs), graphene quantum dots (GQDs), black phosphorus quantum dots (BPQDs), ZnO quantum dots (ZnO QDs). We also discuss the challenges and prospects of NHM-QDs based materials in drug delivery field.

The Sn-based alloy anode materials have attracted wide interest due to their excellent capacity and lower voltage platform during the sodium storage process. Unfortunately, a huge volume change causes the Sn-based anode materials to be easily broken during the charging/discharging processes, resulting in capacity degradation. Herein, the composites composed of Ni-Sn alloy quantum dots embedded in porous carbon nanosheets (Ni-Sn@ PNC) have been synthesized by a simple template method. And the morphological structure and electrochemical performance of the composites Ni₃Sn₄@PNC, Ni₃Sn₂@PNC and PNC have been investigated using structural characterization techniques and electrochemical measurements. The results show that the Ni₃Sn₄@PNC exhibits the best performance among the samples as anodes for sodium-ion batteries. The Ni₃Sn₄@PNC anode delivers a high capacity of 232.7 mAh/g after 100 cycles at 100 mA/g, and the outstanding cycle stability with a capacity retention rate of 81.6% over 1000 cycles at 400 mA/g. The superior electrochemical performance of Ni-Sn alloy anode materials is attributed to the synergistic effect of Ni₃Sn₄ quantum dot and porous carbon nanoplates, shortening the transport distance of charged species, providing high contact area of the electrolyte and active materials, and increasing the reaction active sites. This work provides a feasible strategy for the exploration of new alloy anodes for sodium-ion batteries.

Quantum dots (QDs) are semiconductor nanocrystals with a size of 1-10 nm, which have special optical, electrical, and magnetic properties. They have great prospects in the fields of quantitative analysis, biomedicine, and solar cells. Among them, copper indium sulfide (CuInS₂) ternary QDs which has stable fluorescence properties, is considered to be an ideal green non-toxic environmentally friendly fluorescent nanomaterial because it does not contain toxic heavy metal elements such as cadmium or lead. This article introduces the research progress of CuInS₂ ternary QDs in detail. Starting from the basic properties, its optical properties are expounded. The different synthesis methods of CuInS₂ ternary QDs in organic and aqueous phases, and how to enhance its water solubility and biocompatibility by surface modification of functional molecules for meeting the requirements of biomedical applications are introduced. At the same time, the research progress of CuInS₂ ternary QDs in the quantitative detection of biomolecules, in vitro cell imaging and in vivo bioimaging is summarized, and the problems to be solved in the development of this kind of materials are prospected.

Semiconductor nanocrystals have quantum size effect and unique optical properties, which can be widely used in optoelectronic devices, biomarkers, solar cells, photocatalysis and so on. Therefore, semiconductor nanocrystals have become a research hotspot of more and more researchers. However, among many application limitations, high-performance QDs materials (II-VI or IV-VI) usually contain highly toxic elements such as Cd or Pb. Large amount of preparation and use of such materials will not only do great harm to human body, but also cause environmental and ecological problems. So the design and development of QDs materials with low toxicity is one of the research frontiers at present. By controlling the reaction conditions, surface coating and doping, researchers can control the properties of InP materials, letting it be better used in various fields.

Due to the simple preparation,steady performance, high efficiency of fluorescence quantum conversion, low cost, and environmental friendliness, carbon quantum dots (CQDs) have received considerable attention. In this paper, the methods of preparing CQDs and their applications in metal ion detection were reviewed. Finally, the new insight and novel thought were provided for exploring new preparation methods and key techniques of environmental applications for CQDs.

Nitrogen and sulfur-doped carbon dots (N,S-CDs) were successfully synthesized by hydrothermal method with mushroom and lysine as precursor. The morphology, optical properties and applications of N,S-CDs were studied. In the structure characterization, N,S-CDs were homogeneous spheres. N and S elements were successfully doped with heteroatom and functional groups on the surface of N,S-CDs. In the optical performance, the experimental results show that the N,S-CDs had favorable fluorescent properties including high quantum yield (14.27%) and ideal fluorescent stability. In view of the combination of Fe (Ⅲ) ion and the carboxyl group on the surface of N,S-CDs, the fluorescence of N,S-CDs could be effectively quenched. Based on the above characteristics of N,S-CDs, it could be used as a fluorescent probe to detect Fe³⁺ with a minimum detection limit of 280 nmol/L.

CdSe∶X/ZnS doped core-shell quantum dots were successfully synthesized in aqueous solution by a green synthetic route. The structural and spectroscopic properties of the synthesized products were studied in detail via using a variety of analytical methods. XRD results show that the diffraction peaks of core-shell quantum dots shifted to high angle direction relative inner CdSe quantum dots, and the diffraction peaks of doped core-shell quantum dots also moved to high angle region with respect to undoped quantum dots. The obtained quantum dots had the average grain size of about 2.3 nm. SEM results display that the shape of the produced quantum dots was nearly spherical. Compared with the corresponding bulk materials, the absorption peaks of the quantum dots displayed a significant blue shift, which revealed the obvious quantum confinement effect. The synthesized samples had good hydrophilicity, and Tyndall effect appeared under the infrared light irradiation. The FT-IR results exhibit that ligand MPA successfully was coated on the surface of quantum dots.

Zinc-based quantum dots have been widely used in analysis detection and biomarker due to their unique optical properties, low toxicity and good biocompatibility. Based on the research progress, in this paper, the synthesis methods and functionalized modifications, as well as the application of zinc-based quantum dots in the field of biochemical sensing were systematically described. The development trends and prospects of application of zinc-based quantum dots were also discussed in detail.

Although the fluorescence performance of carbon quantum dots (CQDs) has been extensively studied, few people pay attention to the phosphorescence phenomenon and the mechanism of CQDs. The carbon quantum dots are fixed in the barium sulfate matrix by electrostatic self-assembly. The carbon quantum dots, as the core attraction active ion, provides the luminescence center for the room temperature phosphor composite material. The obtained materials (named CQDs@BaSO₄) are not only scattered in the water to show unexpected room temperature phosphorescence emission, but also steadily dispersed in acid/alkali phosphorescence. Under excitation of 365 nm, the long phosphorescence lifetime of CQDs@BaSO₄ composite material is 281 ms and the displayed average lifetime of phosphorescence is 251 ms. The phosphorescence mechanism were studied. The triplet state of aromatic carbonyl compounds on the surface of carbon dots and the fact that BaSO₄ molecular can effectively rigidize these aromatic carbonyl radical groups suppress phosphorescence of the composite in the non-radiative passivating route. Based on the advantage of the phosphorescent materials performance, its anti-counterfeiting inkpad material was successfully made and its application in the phosphorescence anti-counterfeiting was also discussed.

In this paper, graphene quantum dots were synthesized by hydrothermal method, and the synthesized ones were also characterized. Prepared process was in details as following six steps: (1) preparing graphene oxide by employing the improved Hummers method; (2)reducing graphene oxide by sodium borohydride and sodiumcitrate; (3)preoxidizing grapheme with sulfuric and nitricacid;(4) expanding treatment;(5) treating the above product by hydrothermal method;(6) dialyzing the solution for seven days to obtain the graphene quantum dots. Ultraviolet spectrum, fluorescence spectral, as well as the electrochemical and electroluminescent analysis was employed to character the final product. The result showed that the synthesized graphene quantum dots had good ultraviolet and fluorescence response signals and stability of the cheniluminescence.

InAs quantum dots (QDs) grown by indium droplet epitaxy at different substrate temperatures, without or with annealing are reported in this work. At last, a physical model is build. Indium droplets form quantum wires (QWs) along the [11-0] direction at first, then divide into short parts to maintain the minimum surface energy, and these parts become the nuclei of quantum dots. While substrate temperature increases from 460 to 480 ℃, parts coming from the quantum wires become more as well as QDs, at the same time, the number of QWs decreases, which leads to the increase of nanostructure’s average height from 4.09 to 4.58 nm. After the annealing introduced to the experiment under the condition of substrate temperature 480 ℃, QDs are the only nanostructure in the scanning area with its average height increases to 8.56 nm. It can be speculated that the growth of InAs quantum dots by indium droplet epitaxy is a progress which form QWs at first, then QWs divide into short parts capturing atoms absorbed to the edge of steps because of the influence of the Ehrlich-Schwoebel barriers (ES barriers) to form QDs. Also, the introduction of annealing will promote the QW-to-QDs transformation, and improve the uniformity of QDs’ size. At last, a physical model is build according to the analysis above.

Quantum dot-sensitized solar cells (QDSSCs) have attracted much attention in the past few years because of low cost, easy fabrication, size-dependence bandgap and multiple exciton generation (MEG) of quantum dots (QDs) and high theoretical photoelectric conversion efficiency (PCE). The counter electrode as an important part of QDSSCs is one of the key factors that influence the performance of QDSSCs. This review demonstrates the development of counter electrodes. Furthermore, the classification, preparation methods and the advantages and disadvantages of counter electrodes are introduced in detail. Finally, the future research direction of counter electrodes is prospected.

Graphene quantum dots (GQDs) are considered to be one of the most promising nanomaterials in environmental chemistry, device application and biomedical fields because of the spectral tunable range of their photoluminescence and their stabilities. The investigation of photoluminescence mechanism, the design of fluorescence spectrum and the further development of controllable synthesis methods especially large-scale preparation remains to be challenging in the application of GQDs. In this paper, the GQDs preparation methods including Top-down method, Bottom-up method and surface modification are briefly introduced. The photoluminescence properties and characteristics of GQDs and other quantum dot materials were compared. The influence of quantum confinement effect and edge or surface states on the photoluminescence properties of GQDs is reviewed.

Different thickness of InGaAs quantum dots were prepared through intermittent interruption growth(IIG) of As resource in molecular beam epitaxy (MBE) and the morphologies of them were studied and analyzed by reflection high energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). The results show that the uniformity of quantum dots was improved under intermittent interrupt growth and the morphologies of quantum dots were controlled by the growth temperature and the amount of material deposited. A larger amount of material deposited could lead to higher density and more uniformity of quantum dots could be attained at higher growth temperature in a special range. There were three obvious differences phases such as layer-by-layer growth, formation and self-ripen phases of quantum dot and two transition points which were Stranski-Krastanow (SK) and self-ripen transition in the process of growth of InGaAs quantum dots.

Fluorescence characteristics of silicon carbide quantum dots(SiC-QDs) prepared by chemical corrosion method and labeling mechanism for the living cells of pathogenic fusarium were explored. The results indicate that SiC-QDs photoluminescence intensity reach the maximum value when excitation wavelength is 340nm. Red shift phenomenon of emission wavelength will occur with the excitation wavelength increasing. Because of larger Stokes shift and tunable color fluorescent, near ultraviolet detection for living cells with SiC-QDs fluorescent marking was achieved, which can effectively detect and quantitatively analyze the autofluorescence cells. The results of labeling mechanism for living cells of pathogenic fusarium with SiC-QDs exhibit that quantum dots can reach the cells interior through the clathrin endocytosis action, and achieve homogeneous distribution. So the living cells were marked with stably fluorescent labeling. Moreover, marking model for living cells with SiC-QDs was established based on the experimental results and theoretical analysis.

Graphene quantum dots (GQDs) have attracted widespread attention in recent years. However, because of the heterogeneity of GDQs’ microstructure, research on the photoluminescence mechanism is still not clear. The microstructure of GDQs can be analyzed to the full range by modern analyzing techniques, which has important significances on the study of photoluminescence mechanism of GQDs. Herein, some general characterizing techniques were comparatively reviewed and the recent progress of advanced characterizing techniques, especially combined techniques in the research of GDQs’ microstructure and bio-imaging application was placed emphasis on. Moreover, some perspectives on characterizing techniques and research trends of GQDs were presented.

ZnO is an environmental-friendly semiconductor material with excellent performance. It has a wide application in energy, information, environment, etc, owing to numerous advantages of being abundant, simple preparation and feasible morphology controllable morphology structures. ZnO is commonly used as photoanode materials in dye/quantum dot sensitized solar cells, to loadling light absorber, accepting and transporting electrons. A series of different nanostructures, such as nanoparticles, nanowires, nanosheets and nanoflowers have been used in the sensitized solar cells, and the performance of the sensitized solar cells have been greatly improved via morphology adjusting. This review summarizes the ZnO nanomaterials in the aspect of the single structure and hierarchical structure. It also discusses the recent research progress in dye/quantum dot sensitized solar cells fabricated from ZnO photoanode, and the further trends for improving ZnO nanomaterials based device performance are reviewed as well.

Nanoholes were fabricated on GaAs (001) surface by Ga droplet etching，then InAs quantum dots with varying InAs supply were formation on this surface by molecular beam epitaxy. The condition of sample surface was monitored with a reflection high energy electron diffraction system in situ, scanning tunneling microscopy was utilized for analysis the formation and distribution of quantum dots with increasing InAs supply. The result indicated that InAs will follow the Stranski-Krastanov growth mode on the GaAs flat surface. At the same time, on the nanohole location, the steps in and around nanoholes will restrict the nucleation of quantum dots. However, this restriction will become weaker with increasing InAs supply. Especially, when InAs deposition increased to 2 monolayers, ring-like nanostructures consist of InAs quantum dots with uniform size will be observed on the nanohole location.

To understand the factors which effects the formation of quantum dots (QDs), the kinetic Carlo (KMC) method has been extensively used to simulate QD growth. In this paper, the advantage and the progress of KMC method have been well introduced. Based on the model structure and the interaction potential between atoms, we discussed the QD growth process including the transition from 2 D to 3D growth, the nucleation site, the QD size distribution, and the morphology evolution respectively. Moreover, the calculation progress on the ordered QDs grown on the patterned substrate is also concluded. Our review may give some beneficial guidance for the nanomaterial growth and the consequent device fabrication.

A set of hydrodynamic cavitation reactor is designed according to the principle of hydrodynamic cavitation. Carbon quantum dots (CQDs) are prepared with glucose and alanine as raw material assisted hydrodynamic cavitation in this paper. It is charactered by Fourier transform infrared spectroscopy , X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, high resolution transmission electron microscopy，fluorescence spectrophotometer and UV - visible spectrophotometry photometer. Experimental results show that CQDs were successfully synthesized with batch production assisted hydrodynamic cavitation device. CQDs were of small particle size, good dispersion, uniform particle ,good water solubility， multiple exciting wavelength and high fluorescence intensity, were rich in nitrogen doping and functional groups in the surface .the initial method with adjusted reaction vessel laid a foundation to be applied in small batch laboratory，especially in industrialized batch production

Quantum dots (QDs) as a novel fluorescent nano material with excellent performance of optical, electrochemistry and photoluminescence attract extensive research interest in bioanalysis, medical diagnosis, sensors of electrochemistry, deliver drugs and solar battery. Cyclodextrins are well-known molecular hosts capable of including hydrophobic molecules inside the cavities, which also have fine properties of biocompatibility and solubility. The cyclodextrin had significant progressed in many fields such as fluorescent sensors, innoxious organic synthesis and construction of gene delivery. With the modification of cyclodextrin, the quantum dots have many fire-new properties and attract extensive interest in passed years, and researchers acquire a great achievement in the application of biomedicine and analysis of medicine. This review, which follows the classification of selective recognition for bioactive molecules, drug molecules and the other molecules with cyclodextrin-modified quantum dots, summarizes the representative research and applications in these aspects from 2009 to update. Meanwhile, the prospects and research directions of cyclodextrin-modified quantum dots are given based on the analysis of this research filed.

Abstract: Carbon quantum dots (CQDs, C-dots or CDs), a new type of carbon materials, less than 10 nm in size, have a lot of excellent performance, such as superior solubility in water, chemical inertness, low toxicity, easy functionalization, resistance to photobleaching and good photostability, having attracted widespread attention as a rising star in nanocarbon family in recent years. Since the phenomenon of bright colorful light from carbon quantum dots was reported in 2006, research groups around the world have begun to investigate the carbon quantum dots. CQDs produced from various synthetic strategies find their wide values in more and more fields, especially in biomedicine, optoeletronics, catalysis and sensors. In this review, we describe the recent progress in the field of CQDs, focusing on their synthetic methods, size control, modification strategies, photoelectric properties, luminescent mechanism, and applications in biomedicine, optoelectronics, catalysis and sensor issues.

Carbon quantum dots (CQDs) and their surface amine modification were prepared in a autoclave, and TiO2 was produced in the hydrothermal conditions, then CQDs was incorporated intoTiO2.Fluorescence intensity of amino-functional CQDs was higher than original CQDs, while the fluorescence of composite catalysts was quenched under the same conditions, and absorption capacity was strengthened in visible solar wavelength range. Photocatalytic property of single CQDs and TiO2 were both weak, composite catalysts can accelerate the degradation of methylene blue (MB). Ammonia-capped CQDs and TiO2 composite catalyst can degrade MB completely in 15 minutes , and ethylenediamine-capped CQDs and TiO2 composite catalyst only need 10 minutes. This showed that the availability of visible light increased.

Ternary CuInS quantum dots were synthesized by decomposition of precursor, and the effect of synthesis parameter on the morphology and optical properties of CuInS nanocrystals was investigated. It is found that the particle size and optical property of CuInS crystals could be affected by reaction time and temperature. With increasing reaction time, the CuInS nanocrystals grow larger, accompanied with appearance of rodlike crystals and red shift of the peak of the fluorescent emission spectra. With increasing reaction temperature, the nucleation rate and the growing rate of nanocrystals increase as well as the particle size, also the shape of nanocrystals can vary from single sphere to mixing of sphere and rod, and red shift of emission peak will happen as well. Analysis of X-ray photoelectron spectrometer shows that as-synthesized particles are nanocrystals. This work would build foundation for further manufacture of non-toxic quantum dots light-emitting devices (QLEDs).

Abstract: A novel technology was developed for the synthsis of thioglycolic acid(TGA)-capped CdTe quantum dots(QDs) while sodium tellurite was used as the tellurium source. The influence of the concentration of Cd2+ and Cd2+-TGA precursor holding time in room temperature on the photoluminescence(PL) and fluorescence quantum yield(QY) were systematically investigated. The obtained QDs were characterized by X-ray powder diffraction(XRD) and transmission electron microcopy(TEM). The results show that the CdTe QDs are of zinc-blended crystal structure in a sphere-like shape. The CdTe QDs with maximum quantum yiele of 48.4% with the condition of the Cd2+-TGA precursors were static for 50min in room temperature before backflow and the concentration of Cd2+ was 0.00067mol/L.

In this paper, due to the unique optical properties, water-soluble CdSe/CdS/ZnS multilayer core shell QDs/DADA with stable fluorescence property were synthesized based on ligand-exchange method between quantum dots and 1,12-Dodecanediamine(DADA), then were dissolved in aqueous solution of different pH values. The testing results showed that QDs/DADA solution has photoresponse to the pH value, which fluorescence intensities increased and subsequently decreased gradually with the enhangcement of pH values.

Abstract: Double-layers Ge/Si quantum dot samples were grown on Si(100) substrate by ion beam sputtering system. The influence of buried strain on the growth of islands on the upper layer was studied by varying the thickness of Si spacer-layer and Ge deposition. When the thickness of spacer-layer is thin, the results show that a reduction of wetting-layer thickness of islands on the upper layer. In addition, with increasing the thickness of Ge deposition, the growth of islands on the second layer is modulated. Increasing the thickness of spacer-layer, the growth of islands on the second layer follows the buried dots. The change of growth mode is explained by the non-uniform strain field induced by the buried islands and passing through the spacer-layer.

Abstract: A series of Ge quantum dot samples at different C-induced layer temperature are grown on n-Si(100) substrates by ion beam sputtering. Their morphology and structure are characterizated by using AFM and Raman spectra. Our results show that when the growth temperature of C layer increases from 600℃ to 700℃, the density of the quantum dots decreases to a minimum and the crystalline becomes worse;the Si composition increases in quantum dots at the same time. When the growth temperature of C layer increases from 700℃ to 800℃, the density of the quantum dots increases to a maximum and the crystalline turns to better; while the composition of Si in Ge quantum dots reduces.

Recently, the newly environmental friendly I-III-VI semiconductor quantum dots (QDs) AgInS2 has received significant progress by virtue of its excellent properties of quantum dots and the advantage of low-toxic. Therefore, it is expected to replace Cd-based quantum dots in various applications. Focus on the advances at home and abroad, the status and the existing problems of AgInS2 quantum dots are summerized and discussed. Furthermore, the prospects of the related research are presented.

Using 3-Mercaptopropionic acid(MPA) as surface coated agent,Mn2+-doped water- soluble quantum dots of ZnS were synthesized by co-precipitation method.The effects of Mn2+ dopant and doping amount on microstructure, morphology and photoluminescence properties of the As-products were researched by X-ray diffraction, transmission electron microscopy, UV-visible absorption spectrometer,and fluorescence spectrophotometer.The results show that the products were irregular spherical cubic zinc blender ZnS with sizes around 9.7nm. Photoluminescence spectra analysis show that Mn2+-doped ZnS quantum dots appeared two emission peaks located at 587nm and 637nm which indicated ZnS surface emitting and Mn2+: 4T1-?6A1 level characteristic luminescence respectively.The synthesis mechanism of Mn2+-doped ZnS quantum dots was studied by infrared spectroscopy.

CdSe,CdSe/ZnS and Eu doped QDs were synthesized in LSS system. The QDs were characterized by TEM, XRD , PL and EDX. The TEM results show that the QDs have uniform size and morphology . And the results of XRD show CdSe/ZnS QDs belong to hexagonal crystal system . The PL of the samples prove that the CdSe QDs coated with suitable thickness ZnS have a remarkable rise in Luminous efficiency and the FWHM(the full width half maximum) . And we analyzed this results. The CdSe QDs doped with Eu have a new emission peak.in red area, while the CdSe(Eu)/ZnS QDs do not. We also clarified the causes of this phenomenon .

GSH-stabilized high-luminescent Zn1-xCdxTe quantum dots (QDs) were prepared by microwave irradiation method in aqueous phase presented. The obtained ternary QDs were characterized by X-ray diffraction pattern (XRD), high resolution transmission electron microscopy (HRTEM), UV-vis absorption and photoluminescence (PL) spectra. The effects of reaction time, Cd2+/Zn2+ feed ratio, reaction temperature, pH of the precursor solution on the PL properties of ternary QDs were investigated in the present work. The MTT assay method was used to evaluate the cytotoxicity of GSH-Zn1-xCdxTe ternary QDs. Furthermore, the obtained ternary QDs were conjugated with β-actin antibody as fluorescence probes for cellular labeling.

Multi-period vertically stacked InGaAs quantum dots were grown by molecular beam epitaxy in Stranski-Krastanov mode with interruption of source, the multilayered 2D-arrays In0.43Ga0.57As/GaAs(001) dots-in-a-well were obtained with tunable dimension and density. The epitaxy structure of sample is composed of 500nm GaAs buffer layer, multi-period stacked InGaAs quantum dots and 60 monolayer GaAs. The growth process was monitored real time with reflection high energy electron diffraction, the surface morphology of sample was scanned with scanning tunneling microscope after anneal.

The efficiency of the quantum dot sensitized solar cell have broken through 5% up to now. But there is a big distance between the efficiency of quantum dot sensitized solar cell with that of the dye sensitized solar cell which is 12%. Five points which are charge recombation, light harvesting, structure of photoanode, electrolyte and counter electrode were put forward as the reason for the low efficiency of the quantum dot sensitized solar cell. Meanwhile the solution to them by researchers in the field of quantum dot sensitized solar cell was also introduced.