scholarly journals Sexithiophenes as efficient luminescence quenchers of quantum dots

2011 ◽  
Vol 7 ◽  
pp. 1722-1731 ◽  
Author(s):  
Christopher R Mason ◽  
Yang Li ◽  
Paul O’Brien ◽  
Neil J Findlay ◽  
Peter J Skabara
Keyword(s):  
Quantum Dots ◽  
Cyclic Voltammetry ◽  
Quantum Dot ◽  
Absorption Spectroscopy ◽  
Photoluminescence Spectroscopy ◽  
End Capping

Sexithiophenes 1a and 1b, in which a 4-(dimethylamino)phenyl unit is incorporated as an end-capping group, were synthesised and characterised by cyclic voltammetry, absorption spectroscopy and UV–vis spectroelectrochemistry. Additionally, their ability to function as effective luminescence quenchers for quantum dot emission was studied by photoluminescence spectroscopy and compared with the performance of alkyl end-capped sexithiophenes 2a and 2b.

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>

scholarly journals Monolayer Quantum-Dot Based Light-Sensor by a Photo-Electrochemical Mechanism

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 817
Author(s):  
Sitansu Sekhar Nanda ◽  
Minjik Kim ◽  
Sung Jong Yoo ◽  
Georgia C. Papaefthymiou ◽  
Dong Kee Yi
Keyword(s):  
Quantum Dots ◽  
Cyclic Voltammetry ◽  
Quantum Dot ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Photocurrent Density ◽  
Light Illumination ◽  
Indium Tin Oxide Electrode ◽  
Photo Sensor ◽  
Cadmium Selenium

Monolayer nanocrystal-based light sensors with cadmium-selenium thin film electrodes have been investigated using electrochemical cyclic voltammetry tests. An indium tin oxide electrode system, with a monolayer of homogeneously deposited cadmium-selenium quantum dots was proven to work as a photo-sensor via an electrochemical cell mechanism; it was possible to tune current densities under light illumination. Electrochemical tests on a quantum dot capacitor, using different sized (red, yellow and green) cadmium-selenium quantum dots on indium tin oxide substrates, showed typical capacitive behavior of cyclic voltammetry curves in 2M H2SO4 aqueous solutions. This arrangement provides a beneficial effect in, both, charge separation and light sensory characteristics. Importantly, the photocurrent density depended on quantum yield rendering tunable photo-sensing properties.

scholarly journals Quantum dot-imprinted polymers with size and shell-selective recognition properties

2015 ◽  
Vol 51 (80) ◽  
pp. 14933-14936 ◽  
Author(s):  
S. Gam-Derrouich ◽  
C. Bourdillon ◽  
W. Daney De Marcillac ◽  
L. Coolen ◽  
A. Maître ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Surface Chemistry ◽  
Photoluminescence Spectroscopy ◽  
Selective Recognition ◽  
Imprinted Polymers ◽  
Recognition Ability

Bulk quantum dots imprinted polymers were designed for the detection and speciation of nanoparticles based on their size, shape and surface chemistry. Their recognition ability was demonstrated by photoluminescence spectroscopy.

NiAg-graphene quantum dot-graphene hybrid with high oxidase-like catalytic activity for sensitive colorimetric detection of malathion

2021 ◽  
Author(s):  
Xu Dan ◽  
Ruiyi Li ◽  
Qinsheng Wang ◽  
Yongqiang Yang ◽  
Haiyan Zhu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Catalytic Activity ◽  
Quantum Dot ◽  
Colorimetric Detection ◽  
Graphene Quantum Dots ◽  
Functionalized Graphene ◽  
Graphene Quantum Dot ◽  
Nickel Silver

The paper reports the synthesis of nickel-silver-graphene quantum dot-graphene hybrid. Histidine-functionalized graphene quantum dots (His-GQDs) were bonded to graphene oxide (GO) and then combined with Ni2+ and Ag+ to form...

scholarly journals Effect of Growth Temperature on the Characteristics of CsPbI3-Quantum Dots Doped Perovskite Film

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4439
Author(s):  
Shui-Yang Lien ◽  
Yu-Hao Chen ◽  
Wen-Ray Chen ◽  
Chuan-Hsi Liu ◽  
Chien-Jung Huang
Keyword(s):  
Thin Films ◽  
Thermal Stability ◽  
Quantum Dots ◽  
Quantum Dot ◽  
Growth Temperature ◽  
Electron Mobility ◽  
Surface Defects ◽  
Different Temperatures ◽  
Pb Doping ◽  
Pristine Film

In this study, adding CsPbI3 quantum dots to organic perovskite methylamine lead triiodide (CH3NH3PbI3) to form a doped perovskite film filmed by different temperatures was found to effectively reduce the formation of unsaturated metal Pb. Doping a small amount of CsPbI3 quantum dots could enhance thermal stability and improve surface defects. The electron mobility of the doped film was 2.5 times higher than the pristine film. This was a major breakthrough for inorganic quantum dot doped organic perovskite thin films.

Carbon quantum dot-sensitized hollow TiO2 spheres for high-performance visible light photocatalysis

2021 ◽  
Author(s):  
Xianfeng Zhang ◽  
Zongqun Li ◽  
Shaowen Xu ◽  
Yaowen Ruan
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Visible Light ◽  
Photocatalytic Degradation ◽  
High Performance ◽  
Carbon Quantum Dots ◽  
Visible Light Photocatalysis ◽  
Carbon Quantum Dot ◽  
Visible Light Photocatalytic

TiO2/CQD composites were synthesized through carbon quantum dots covalently attached to the surface of hollow TiO2 spheres for visible light photocatalytic degradation of organics.

scholarly journals Flexible and efficient perovskite quantum dot solar cells via hybrid interfacial architecture

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Long Hu ◽  
Qian Zhao ◽  
Shujuan Huang ◽  
Jianghui Zheng ◽  
Xinwei Guan ◽  
...  
Keyword(s):  
Thin Film ◽  
Quantum Dots ◽  
Solar Cells ◽  
Quantum Dot ◽  
High Performance ◽  
Mechanical Stability ◽  
Mechanical Adhesion ◽  
Perovskite Quantum Dots ◽  
Efficient Charge ◽  
Photovoltaic Technologies

AbstractAll-inorganic CsPbI3 perovskite quantum dots have received substantial research interest for photovoltaic applications because of higher efficiency compared to solar cells using other quantum dots materials and the various exciting properties that perovskites have to offer. These quantum dot devices also exhibit good mechanical stability amongst various thin-film photovoltaic technologies. We demonstrate higher mechanical endurance of quantum dot films compared to bulk thin film and highlight the importance of further research on high-performance and flexible optoelectronic devices using nanoscale grains as an advantage. Specifically, we develop a hybrid interfacial architecture consisting of CsPbI3 quantum dot/PCBM heterojunction, enabling an energy cascade for efficient charge transfer and mechanical adhesion. The champion CsPbI3 quantum dot solar cell has an efficiency of 15.1% (stabilized power output of 14.61%), which is among the highest report to date. Building on this strategy, we further demonstrate a highest efficiency of 12.3% in flexible quantum dot photovoltaics.

65‐3: Quantum Dot Light‐emitting Diodes with High Color Purity RGB Cadmium‐Free Quantum Dots

2021 ◽  
Vol 52 (1) ◽  
pp. 953-956
Author(s):  
Tatsuya Ryowa ◽  
Yusuke Sakakibara ◽  
Tadashi Kobashi ◽  
Keisuke Kitano ◽  
Masaya Ueda ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Light Emitting Diodes ◽  
Color Purity ◽  
Light Emitting ◽  
High Color Purity

Enhanced Normal-Incident Absorption of Quantum-Dot Infrared Photodetectors With Smaller Quantum Dots

2008 ◽  
Vol 20 (14) ◽  
pp. 1240-1242 ◽  
Author(s):  
Chi-Che Tseng ◽  
Shu-Ting Chou ◽  
Yi-Hao Chen ◽  
Cheng-Nan Chen ◽  
Wei-Hsun Lin ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Infrared Photodetectors ◽  
Quantum Dot Infrared Photodetectors
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