One-Step Synthesis of CdSe Quantum Dots by Using Hydrazine Hydrate Reduction of Selenium Dioxide

2018 ◽  
Vol 71 (7) ◽  
pp. 524 ◽  
Author(s):  
Rongfang Wang ◽  
Xingming Wei ◽  
Jun Xie ◽  
Bomei Wang ◽  
Xiaotong He
Keyword(s):  
Quantum Dots ◽  
Hydrazine Hydrate ◽  
Selenium Dioxide ◽  
Water Soluble ◽  
Molar Ratio ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
Original Solution ◽  
Transmission Electron ◽  
Average Size

Hydrazine hydrate was used as a novel reducing agent for the synthesis of water soluble and stable cadmium selenide (CdSe) quantum dots (QDs). The as-prepared CdSe quantum dots were investigated by X-ray powder diffraction, high-resolution transmission electron microscopy, photoluminescence, and UV-vis absorption spectroscopy analyses. The results show that the as-prepared CdSe QDs possess a cubic crystal structure and an average size of 2 nm. The effects of the pH of the original solution, thioglycollic acid (TGA)/Cd2+ molar ratio (nTGA/nCd2+), and the Cd/Se molar ratio on the luminescence properties of CdSe QDs were also systematically analysed.

scholarly journals One-Step Synthesis of High-Quality Water-Soluble CdSe Quantum Dots Capped byN-Acetyl-L-cysteineviaHydrothermal Method and Their Characterization

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Chunjin Wei ◽  
Jinyu Li ◽  
Fang Gao ◽  
Shuxia Guo ◽  
Yongcui Zhou ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Photoelectron Spectroscopy ◽  
Ph Value ◽  
Water Soluble ◽  
Molar Ratio ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
Hydrothermal Route ◽  
Experimental Conditions ◽  
One Step

Novel water-soluble CdSe quantum dots (QDs) have been prepared withN-acetyl-L-cysteine as new stabilizer through a one-step hydrothermal route. The influence of experimental conditions, including reaction time, molar ratio of reactants, and pH value, on the luminescent properties of the obtained CdSe QDs has been systematically investigated. The characterization of as-prepared QDs was carried out through different methods. In particular, we realized qualitative and semiquantitative studies on CdSe QDs through X-ray photoelectron spectroscopy and electron diffraction spectroscopy. The results show that the as-prepared CdSe QDs exhibit a high quantum yield (up to 26.7%), high stability, and monodispersity and might be widely used in biochemical detection and biochemical research.

Optimized Synthesis of Water-Soluble and Small-Size CdSe Quantum Dots

2011 ◽  
Vol 266 ◽  
pp. 46-50
Author(s):  
Jiao Yun Xia ◽  
Jun Long Tang
Keyword(s):  
Aqueous Solution ◽  
Quantum Dots ◽  
Water Soluble ◽  
Cdse Quantum Dots ◽  
Key Factors ◽  
Cdse Qds ◽  
High Quality ◽  
Synthesis Route ◽  
Initial Ph

An optimized synthesis route was applied for controlling the preparation of CdSe quantum dots (QDs) in an aqueous solution. Some key factors which influencing the properties of CdSe QDs, such as initial pH, ratio of precursor etc, were investigated. The as-prepared products have been characterized by TEM, XPS, XRD, UV-Vis and fluorescence (FL) spectra. The result showed that the high-quality CdSe QDs with 3 nm was obtained. The experiments also conformed that the CdSe QDs with better FL properties were obtained with properly initial pH, 5, suitably [Cd2+] / [SeSO3 2-], range from 1:0.25 to 1:0.75 and the ratio of [Cd2+] / [TGA] is 1:2~1:3.

FLUORESCENCE STUDY OF CdSe QUANTUM DOTS SUSPENDED IN LIQUID PARAFFIN

NANO ◽  
2010 ◽  
Vol 05 (06) ◽  
pp. 357-359 ◽  
Author(s):  
S. C. DEY ◽  
R. DAS ◽  
S. S. NATH ◽  
R. BHATTACHERJEE
Keyword(s):  
Quantum Dots ◽  
Liquid Paraffin ◽  
Green Light ◽  
Cdse Quantum Dots ◽  
Fluorescence Study ◽  
Optical Source ◽  
Chemical Route ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Average Size

Here we report a safer, easier, and quicker chemical route for synthesis of CdSe quantum dots (QDs), followed by their characterizations by UV/vis Spectroscopy (UV/vis), X-ray diffraction study (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and fluorescence (FL) spectroscopy. The average size of the quantum dots is 7.5 nm. Fluorescence study reveals that CdSe quantum dots emit green light when excited by optical source of wavelength of 550 nm or less.

Synthesis of High-Performance Aqueous CdSe Quantum Dots Based on Combination of Se Source as Vapor-Phase and Hydrothermal Method

2010 ◽  
Vol 663-665 ◽  
pp. 96-99
Author(s):  
Heng Kang Qiu ◽  
Yue Shen ◽  
Lin Jun Wang ◽  
Jian Cheng Zhang ◽  
Kai Feng Qin
Keyword(s):  
Quantum Dots ◽  
Hydrothermal Method ◽  
Vapor Phase ◽  
High Performance ◽  
Hydrothermal Reaction ◽  
Water Soluble ◽  
Quantum Yields ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
Visible Absorption

High performance aqueous CdSe quantum dots (QDs) have been prepared by combination of Se source as vapor-phase and hydrothermal method. The main advantages of this approach included: one is to utilize H2Se vapor as a higher pure selenium source to make the prepared QDs have little other impurities, another is to obtain the QDs with characteristics of more rapid growth in the hydrothermal reaction. The as-prepared products have been characterized by ultraviolet-visible absorption spectra, photoluminescence spectroscopy (PL), X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy dispersive spectroscopy (EDS) analysis etc. The results show the as-synthesized water-soluble CdSe nanoparticles possess higher purity and quantum yields (QY), favorable narrow photoluminescence band with full width of half-maximum (FWHM) down to 40 nm, better photo-stability, and less synthetic time as compared with aqueous CdSe QDs obtained by other methods.

scholarly journals Structural and optical investigation of CdSe quantum dots

2013 ◽  
Vol 8 (2) ◽  
pp. 83-88
Author(s):  
Neupane Dipesh
Keyword(s):  
Quantum Dots ◽  
Large Scale ◽  
Room Temperature ◽  
Spherical Shape ◽  
Cdse Quantum Dots ◽  
Optical Investigation ◽  
X Ray ◽  
Transmission Electron ◽  
Engineering And Technology ◽  
Average Size

CdSe semiconducting Quantum dots were prepared by a chemical method at a room temperature. X-ray powder diffraction and transmission electron microscope measurements conformed a hexagonal cubic crystalline phase of Cdse semiconducting Quantum dots of about 15 nm average size with nearly spherical shape. The absorption and photoluminescence spectra of the CdSe quantum dots were strongly shown blue shifted due to size quantization. The present study describes a simultaneous and highly reproducible large scale synthesis of highly luminescent CdSe Quantum dots. Kathmandu University Journal of Science, Engineering and Technology Vol. 8, No. II, December, 2012, 83-88 DOI: http://dx.doi.org/10.3126/kuset.v8i2.7329

Preparation of Helical Monosubstituted Polyacetylene@CdSe Quantum Dots Composite and its Application for Low Infrared Emissivity

2014 ◽  
Vol 1044-1045 ◽  
pp. 88-91
Author(s):  
Xiao Hai Bu ◽  
Yu Ming Zhou ◽  
Man He ◽  
Tao Zhang ◽  
Hu Chuan Wang
Keyword(s):  
Quantum Dots ◽  
Optically Active ◽  
Helical Conformation ◽  
Cdse Quantum Dots ◽  
Infrared Emissivity ◽  
X Ray Diffraction ◽  
Cdse Qds ◽  
Transmission Electron ◽  
Ft Ir ◽  
Ester Linkage

Helical monosubstituted polyacetylene@CdSe quantum dots (HPA@CdSe QDs) nanocomposites were fabricated by grafting helical HPA polymers onto the surface of semiconductor QDs through ester linkage. Optically active HPA derived from chiral serine was polymerized by a rhodium zwitterion catalyst, and evidently proved to adopt a predominately single-handed helical conformation. The HPA@QDs nanocomposites were characterized by Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The results indicate that the HPA matrix exhibits an enhancement in thermal stability after hybridization with CdSe QDs, while the QDs can maintain their original crystalline structure during the grafting process. The infrared emissivity property of the HPA@QDs nanocomposites at 8-14 μm was further investigated. These data demonstrated that the HPA@QDs composite film with doped CdSe QDs possesses an infrared emissivity value of 0.393, which was much lower than pristine HPA and QDs. This might be attributed to the incorporation of optically active helical HPA and semiconductor QDs in a hybrid phase and their strengthened interfacial interaction.

scholarly journals Size Dependent Optical Nonlinearity and Optical Limiting Properties of Water Soluble CdSe Quantum Dots

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Anju K. Augustine ◽  
S. Mathew ◽  
P. Radhakrishnan ◽  
V. P. N. Nampoori ◽  
M. Kailasnath
Keyword(s):  
Quantum Dots ◽  
Nonlinear Behavior ◽  
Optical Limiting ◽  
Optical Nonlinearity ◽  
Water Soluble ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
High Laser

We present third-order optical nonlinear absorption in CdSe quantum dots (QDs) with particle sizes in the range of 4.16–5.25 nm which has been evaluated by the Z-scan technique. At an excitation irradiance of 0.54 GW/cm2 the CdSe QDs exhibit reverse saturation indicating a clear nonlinear behavior. Nonlinearity increases with particle size in CdSe QDs within the range of our investigations which in turn depends on the optical band gap. The optical limiting threshold of the QDs varies from 0.35 GW/cm2 to 0.57 GW/cm2 which makes CdSe QDs a promising candidate for reverse-saturable absorption based devices at high laser intensities such as optical limiters.

scholarly journals ZnSe Quantum Dots through a Facile one Pot Synthesis Process

2015 ◽  
Vol 34 ◽  
pp. 73-78
Author(s):  
Irtiqa Syed ◽  
Santa Chawla
Keyword(s):  
Quantum Dots ◽  
Band Gap ◽  
Quantum Confinement Effect ◽  
Hexagonal Phase ◽  
Fluorescence Decay ◽  
Synthesis Process ◽  
One Pot ◽  
One Pot Synthesis ◽  
Transmission Electron ◽  
Average Size

A novel one pot synthesis approach in oleic acid medium was employed to obtain monophasic ZnSe quantum dots (QD) of average size 3.7nm. The QDs were well crystalline in hexagonal phase as revealed by x-ray diffraction and high resolution transmission electron microscopy (HRTEM) studies. The ZnSe QDs exhibit sharp emission peak in the blue (465nm) with 385picosecond fluorescence decay time. The theoretical band gap corresponding to 3.7nm ZnSe QDs matched well with the measured 3.11eV band gap of synthesized QDs which thus showed quantum confinement effect.

SYNTHESIS AND CHARACTERIZATION OF FERROELECTRIC NANOCRYSTAL POWDERS OF SrBi2Ta2O9 BY A POLYMERIZABLE COMPLEX METHOD

2005 ◽  
Vol 19 (15n17) ◽  
pp. 2514-2519 ◽  
Author(s):  
JIN-BO CHENG ◽  
AI-DONG LI ◽  
QI-YUE SHAO ◽  
YUE-FENG TANG ◽  
DI WU
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Thermal Analyses ◽  
Water Soluble ◽  
Complex Method ◽  
Powder Synthesis ◽  
Conventional Solid State Reaction ◽  
Transmission Electron ◽  
Average Size

Ferroelectric nanocrystal powders of SrBi2Ta2O9 (SBT) have been first prepared by a polymerizable complex (PC) route. The bismuth powder, strontium carbonate, and water-soluble tantalum oxalate solution were used as starting materials. Thermal analyses (TGA and DSC), x-ray diffraction (XRD), transmission electron microscopy (TEM), and conventional BET method were explored to characterize the structure, morphology, and specific surface area of PC-derived SBT powders calcined at 500-850 °C. As control samples, SBT powders were also fabricated by metalorganic decomposition (MOD) method. The XRD and TEM results indicate that high pure and well crystalline powders can be obtained at 650 °C with a average size of 50 nm. The PC-derived powder has much larger surface area than MOD-derived powder. The BET value of PC and MOD powder at 750 °C for 2h is 6.7 and 1.5m2/g, respectively. The specific surface area of powder prepared by conventional solid-state reaction is quite low, typically less than 1.5m2/g. Therefore, the feasibility of the polymerizable complex route is demonstrated in the powder synthesis of SBT with large surface area.

scholarly journals Intense Visible Luminescence in CdSe Quantum Dots by Efficiency Surface Passivation with H2O Molecules

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Hyeoung Woo Park ◽  
Do-Hyung Kim
Keyword(s):  
Heat Treatment ◽  
Quantum Dots ◽  
Quantum Yield ◽  
Surface Passivation ◽  
Cdse Quantum Dots ◽  
Cdse Qds ◽  
Effect Of Water ◽  
Visible Luminescence ◽  
Luminescence Efficiency

We have investigated the effect of water (H2O) cooling and heat treatment on the luminescence efficiency of core CdSe quantum dots (QDs). The photoluminescence (PL) quantum yield of the CdSe QDs was enhanced up to ~85%, and some periodic bright points were observed in wide color ranges during the heat treatment of QDs mixed with H2O. The PL enhancement of QDs could be attributed to the recovery of QDs surface traps by unreacted ligands confined within the hydrophilic H2O molecule containers.

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