Study on Photoluminescence Quenching of CdSe Core/Shell Quantum Dots with Organic Charge Transferring Material

2014 ◽  
Vol 981 ◽  
pp. 883-886
Author(s):  
Yu Qiu Qu ◽  
Liu Yang Zhang ◽  
Li Min An ◽  
Hong Wei ◽  
Gui Fan Li
Keyword(s):  
Quantum Dots ◽  
Fluorescence Quenching ◽  
Fluorescence Lifetime ◽  
Spectral Methods ◽  
Shell Structure ◽  
Core Shell ◽  
Cdse Core ◽  
Photoluminescence Quenching ◽  
Molecular Concentration ◽  
Pl Quenching

The effect of organic charge transferring material (CTM) on fluorescence of CdSe/ZnS and CdSe/CdS/ZnS core/shell quantum dots (QDs) are investigated by spectral methods. With the increase of organic molecular concentration, CTM can greatly quench the fluorescence of QDs and shorten the fluorescence lifetime of QDs. In the process of interacting with CTM, the efficiency of fluorescence quenching for CdSe/ZnS is significantly higher than that for CdSe/CdS/ZnS. The results of experiment show that the shell structure of QDs plays the major role in photoluminescence (PL) quenching. The mechanism of PL quenching of QDs is also analyzed.

scholarly journals Conjugation ofE. coliO157:H7 Antibody to CdSe/ZnS Quantum Dots

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
N. T. Vo ◽  
H. D. Ngo ◽  
D. L. Vu ◽  
A. P. Duong ◽  
Q. V. Lam
Keyword(s):  
Quantum Dots ◽  
Shell Structure ◽  
Trioctylphosphine Oxide ◽  
Core Shell ◽  
Cdse Core ◽  
Green Method ◽  
Potential Measurement ◽  
E Coli ◽  
Luminescence Efficiency ◽  
Core Shell Structure

The conjugation of antibody to semiconductor quantum dots plays a very important role in many applications such as bioimaging, biomarking, and biosensing. In this research, we present some results of highly luminescent core/shell structure CdSe/ZnS on which theE. coliantibody was conjugated. The CdSe core was synthesized successfully with chemical “green” method. For biological applications, the capping surfactant, trioctylphosphine oxide, was substituted by a new one, mercaptopropionic acid (MPA), before the antibody attachment step. Finally, theE. coliantibody was attached to quantum dots CdSe/ZnS. Morphology, structure, and optical properties were investigated with PL, UV-Vis, TEM, and XRD methods. The successful ligand substitution and antibody attachment were confirmed by zeta potential measurement, FTIR spectroscopy, and TEM. The results showed quantum dots size of 2.3 nm, uniform distribution, and high luminescence. CdSe/ZnS core/shell structure had better stability and enhanced the luminescence efficiency up to threefold compared with the core CdSe. MPA ligand shifted the initial hydrophobic quantum dots to hydrophilic ones, which helped to dissolve them in organic solvents and attach the antibody.

Internal Atomic-Scale Structure Determination and Band Alignment of II-VI Quantum Dot Heterostructures

2019 ◽  
Author(s):  
Cecilia Gentle ◽  
Yuanheng Wang ◽  
Tyler N. Haddock ◽  
Conner P. Dykstra ◽  
Renske M. van der Veen
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Absorption Spectroscopy ◽  
Shell Structure ◽  
Electronic Band Structure ◽  
Band Alignment ◽  
Atomic Scale ◽  
Core Shell ◽  
Cdse Core ◽  
Electronic Band

<p>This work shows that ZnTe/CdSe core/shell quantum dots synthesized by standard literature procedures in actuality have an alloyed Cd<sup>­</sup><sub>x</sub>Zn<sub>1-x</sub>Te core. We employ X-ray absorption spectroscopy (XAS) at all four <i>K</i>-shell ionization edges (Zn, Te, Cd, Se) and perform a global fitting analysis in order to extract the first-shell bond distances. We combine our XAS results with transmission electron microscopy (TEM) sizing and elemental analyses, which allows us to propose models of the internal particle structure. Our multimodal characterization approach confirms <b>(1) </b>the presence of Cd-Te bonds, <b>(2) </b>cation<b> </b>alloying in the particle core (and the absence of anion alloying), and <b>(3) </b>a patchy pure-phase CdSe shell. We synthesize particles of different shell thicknesses and performed synthetic control studies that allowed us to discard a ZnTe/CdTe/CdSe core/shell/shell structure and confirm the alloyed core/shell structure. Our structural analysis is extended with electronic band structure calculations and UV/vis absorption spectroscopy, demonstrating that the alloyed Cd<sup>­</sup><sub>x</sub>Zn<sub>1-x</sub>Te/CdSe core/shell quantum dots exhibit a direct band gap, different from the predicted type-II band alignment of the intended ZnTe/CdSe core/shell quantum dots. This study highlights the challenges with synthesizing II-VI quantum dot heterostructures and the power of XAS for understanding the internal structure of heterogenous nanoparticles.</p>

Internal Atomic-Scale Structure Determination and Band Alignment of II-VI Quantum Dot Heterostructures

2019 ◽  
Author(s):  
Cecilia Gentle ◽  
Yuanheng Wang ◽  
Tyler N. Haddock ◽  
Conner P. Dykstra ◽  
Renske M. van der Veen
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Absorption Spectroscopy ◽  
Shell Structure ◽  
Electronic Band Structure ◽  
Band Alignment ◽  
Atomic Scale ◽  
Core Shell ◽  
Cdse Core ◽  
Electronic Band

<p>This work shows that ZnTe/CdSe core/shell quantum dots synthesized by standard literature procedures in actuality have an alloyed Cd<sup>­</sup><sub>x</sub>Zn<sub>1-x</sub>Te core. We employ X-ray absorption spectroscopy (XAS) at all four <i>K</i>-shell ionization edges (Zn, Te, Cd, Se) and perform a global fitting analysis in order to extract the first-shell bond distances. We combine our XAS results with transmission electron microscopy (TEM) sizing and elemental analyses, which allows us to propose models of the internal particle structure. Our multimodal characterization approach confirms <b>(1) </b>the presence of Cd-Te bonds, <b>(2) </b>cation<b> </b>alloying in the particle core (and the absence of anion alloying), and <b>(3) </b>a patchy pure-phase CdSe shell. We synthesize particles of different shell thicknesses and performed synthetic control studies that allowed us to discard a ZnTe/CdTe/CdSe core/shell/shell structure and confirm the alloyed core/shell structure. Our structural analysis is extended with electronic band structure calculations and UV/vis absorption spectroscopy, demonstrating that the alloyed Cd<sup>­</sup><sub>x</sub>Zn<sub>1-x</sub>Te/CdSe core/shell quantum dots exhibit a direct band gap, different from the predicted type-II band alignment of the intended ZnTe/CdSe core/shell quantum dots. This study highlights the challenges with synthesizing II-VI quantum dot heterostructures and the power of XAS for understanding the internal structure of heterogenous nanoparticles.</p>

Photoluminescence Quenching of CdSe Core/Shell Quantum Dots by Hole Transporting Materials

2009 ◽  
Vol 113 (5) ◽  
pp. 1886-1890 ◽  
Author(s):  
Youlin Zhang ◽  
Pengtao Jing ◽  
Qinghui Zeng ◽  
Yajuan Sun ◽  
Huaipeng Su ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Core Shell ◽  
Cdse Core ◽  
Photoluminescence Quenching ◽  
Hole Transporting ◽  
Hole Transporting Materials

Photoluminescence quenching and electron transfer in CuInS2/ZnS core/shell quantum dot and FePt nanoparticle blend films

RSC Advances ◽  
2015 ◽  
Vol 5 (39) ◽  
pp. 30981-30988 ◽  
Author(s):  
Jie Hua ◽  
Haibo Cheng ◽  
Xi Yuan ◽  
Yan Zhang ◽  
Mei Liu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Electron Transfer ◽  
Steady State ◽  
Magnetic Nanoparticles ◽  
Quantum Dot ◽  
Core Shell ◽  
Photoluminescence Quenching ◽  
Time Resolved ◽  
Blend Films ◽  
Pl Quenching

The photoluminescence (PL) quenching of CuInS2/ZnS quantum dots (QDs) in blend films with FePt magnetic nanoparticles (MNs) was studied by steady-state and time-resolved PL spectroscopy.

Resistive Switching in CdTe/CdSe Core–Shell Quantum Dots Embedded Chitosan-Based Memory Devices

2021 ◽  
Author(s):  
Zolile Wiseman Dlamini ◽  
Sreedevi Vallabhapurapu ◽  
Olamide Abiodun Daramola ◽  
Potlaki Foster Tseki ◽  
Rui Werner Macedo Krause ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Resistive Switching ◽  
Core Shell ◽  
Cdse Core ◽  
Active Layers ◽  
Ag Electrodes ◽  
Exponential Decrease ◽  
Conductive Bridge ◽  
Bipolar Memory ◽  
State Resistance

In this paper, we report on the resistive switching (RS) and conduction mechanisms in devices consisting of CdTe/CdSe core–shell quantum dots embedded chitosan composites active layer. Two devices with active layers sandwiched between (1) Al and Ag, and (2) ITO and Ag electrodes were studied. Both devices exhibited bipolar memory behavior with [Formula: see text] V and [Formula: see text][Formula: see text]V, for the Al-based device, while [Formula: see text] V and [Formula: see text][Formula: see text]V were observed for the ITO-based device, enabling both devices to be operated at low powers. However, the switching mechanisms of both devices were different, i.e., RS in Al device was attributed to conductive bridge mechanism, while space-charge-limited driven conduction filament attributed the switching mechanism of the ITO device. Additionally, the Al-based device showed long retention ([Formula: see text][Formula: see text]s) and a reasonable large ([Formula: see text]) ON/OFF ratio. Additionally, for this device, we also observed sweeping cycle-induced reversal of voltage polarity of the [Formula: see text] and [Formula: see text]. In contrast, we observed that increasing sweeping cycles resulted in an exponential decrease of the OFF-state resistance of the ITO-based device.

Synthesis and Photoluminescent Properties of Core/Shell Structure ZnS∶Cu/ZnS Quantum Dots

2012 ◽  
Vol 33 (7) ◽  
pp. 736-741 ◽  
Author(s):  
田昕 TIAN Xin ◽  
曹立新 CAO Li-xin ◽  
柳伟 LIU Wei ◽  
苏革 SU Ge ◽  
董博华 DONG Bo-hua
Keyword(s):  
Quantum Dots ◽  
Shell Structure ◽  
Core Shell ◽  
Core Shell Structure
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