Quantum Dot-Single Wall Carbon Nanotube Complexes for Polymeric Photovoltaics

2004 ◽  
Vol 836 ◽  
Author(s):  
Brian J. Landi ◽  
Stephanie L. Castro ◽  
Chris M. Evans ◽  
Herbert J. Ruf ◽  
Sheila G. Bailey ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Carbon Nanotube ◽  
Charge Carriers ◽  
Covalent Attachment ◽  
Mercaptoacetic Acid ◽  
Optical Absorption Spectroscopy ◽  
Synthetic Approach ◽  
Spectroscopy Data ◽  
Photovoltaic Devices ◽  
Transmission Electron

ABSTRACTThe ability to dissociate the photo-generated excitons and transport the resulting charge carriers are the major impediments in improving the efficiency of polymeric solar cells. In order to simultaneously address both of these issues, we have investigated the use of quantum dotsingle wall carbon nanotube (QD-SWNT) complexes as a suitable nanomaterial dopant in these devices. The formation of CdSe-SWNT complexes occurred through covalent attachment of carboxylic acid-functionalized SWNTs with CdSe-aminoethanethiol (AET) quantum dots. An additional synthetic approach was evaluated using both electrostatic and covalent attachment schemes for CuInS2-mercaptoacetic acid (MA) quantum dots and amine terminated SWNTs. The efficacy of each approach is discussed, including the necessary transmission electron microscopy (TEM) and optical absorption spectroscopy data to probe the interactions between nanomaterials. The potential effects of charge transfer between components may have important implications in the efficiency of these materials for polymeric photovoltaic devices.

Photocurrent in a hybrid system of 1-thioglycerol and HgTe quantum dots

2003 ◽  
Vol 789 ◽  
Author(s):  
Hyunsuk Kim ◽  
Kyoungah Cho ◽  
Byungdon Min ◽  
Jong Soo Lee ◽  
Man Young Sung ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Hybrid System ◽  
Wavelength Dependence ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
Electron Hole ◽  
Free Carriers ◽  
Transmission Electron ◽  
Colloidal Method ◽  
First Time

ABSTRACTPhotocurrent mechanism in a hybrid system of 1-thioglycerol and HgTe quantum dots(QDs) was studied for the first time in the intra-red (IR) range. 1-thioglycerol-capped HgTe QDs were prepared using colloidal method in aqueous solution; the synthesis and size of the HgTe QDs were examined by x-ray diffraction, Raman scattering, and high-resolution transmission electron microscopy. Absorption and photoluminescence spectra of the capped HgTe QDs revealed the strong excitonic peaks in the range from 900 to 1100nm, because of their widened band gap due to the shrinkage of their sizes to about 3 nm. The wavelength dependence of the photocurrent for the hybred system of the 1-thioglycerol and HgTe QDs was very close to that of the absorption spectrum, indicating that charge carriers photoexcited in the HgTe QDs give direct contribution to the photocurrent in the medium of 1-thioglycerol. In this hybrid system, the photo-excited electrons in the HgTe QDs are strongly confined, but the photo-excited holes act as free carriers. Hence, in the photocurrent mechanism of the this hybrid system, only holes among electron-hole pairs created by incident photons in the HgTe QDs are transferred to 1-thioglycerol surrounding HgTe QDs and contribute photocurrent flowing in the medium of 1-thioglycerol.

scholarly journals Light-Induced Oxidase Activity of DNAzyme-Modified Quantum Dots

2020 ◽  
Vol 21 (21) ◽  
pp. 8190
Author(s):  
Krzysztof Żukowski ◽  
Joanna Kosman ◽  
Bernard Juskowiak
Keyword(s):  
Quantum Dots ◽  
Catalytic Activity ◽  
Oxidase Activity ◽  
Light Irradiation ◽  
Covalent Attachment ◽  
Radical Scavengers ◽  
Amplex Red ◽  
System A ◽  
Transmission Electron

Here, we report the synthesis of a quantum dot (QD)-DNA covalent conjugate to be used as an H2O2-free DNAzyme system with oxidase activity. Amino-coupling conjugation was carried out between amino-modified oligonucleotides (CatG4-NH2) and carboxylated quantum dots (CdTe@COOH QDs). The obtained products were characterized by spectroscopic methods (UV-Vis, fluorescence, circular dichroizm (CD), and IR) and the transmission electron microscopy (TEM) technique. A QD-DNA system with a low polydispersity and high stability in aqueous solutions was successfully obtained. The catalytic activity of the QD-DNA conjugate was examined with Amplex Red and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate)) indicators using reactive oxygen species (ROS) generated by visible light irradiation. The synthesized QD-DNAzyme exhibited enhanced catalytic activity compared with the reference system (a mixture of QDs and DNAzyme). This proved the assumption that the covalent attachment of DNAzyme to the surface of QD resulted in a beneficial effect on its catalytic activity. The results proved that the QD-DNAzyme system can be used for generation of the signal by light irradiation. The light-induced oxidase activity of the conjugate was demonstrated, proving that the QD-DNAzyme system can be useful for the development of new cellular bioassays, e.g., for the determination of oxygen radical scavengers.

scholarly journals Precursor concentration and temperature controlled formation of polyvinyl alcohol-capped CdSe-quantum dots

2010 ◽  
Vol 1 ◽  
pp. 119-127 ◽  
Author(s):  
Chetan P Shah ◽  
Madhabchandra Rath ◽  
Manmohan Kumar ◽  
Parma N Bajaj
Keyword(s):  
Quantum Dots ◽  
Polyvinyl Alcohol ◽  
Room Temperature ◽  
Near Infrared ◽  
Deep Trap ◽  
Optical Absorption Spectroscopy ◽  
Band Edge Emission ◽  
Cdse Quantum Dots ◽  
Trap States ◽  
Transmission Electron

Polyvinyl alcohol-capped CdSe quantum dots, with a size within their quantum confinement limit, were prepared in aqueous solution at room temperature, by a simple and environmentally friendly chemical method. The size of the CdSe quantum dots was found to be dependent on the concentrations of the precursors of cadmium and selenium ions, as well as on the aging time and the reaction temperature; all of which could be used conveniently for tuning the size of the particles, as well as their optical properties. The synthesized quantum dots were characterized by optical absorption spectroscopy, fluorescence spectroscopy, X-ray diffraction, atomic force microscopy and transmission electron microscopy. The samples were fluorescent at room temperature; the green fluorescence was assigned to band edge emission, and the near-infrared fluorescence peaks at about 665 and 865 nm were assigned to shallow and deep trap states emissions, respectively. The quantum dots were fairly stable up to several days.

FACILE SYNTHESIS OF COLLOIDAL PbS QUANTUM DOTS

2012 ◽  
Vol 11 (06) ◽  
pp. 1240041
Author(s):  
CHAO LIU ◽  
YANG JIANG ◽  
JIAN HUANG ◽  
HONGYAN DUAN
Keyword(s):  
Quantum Dots ◽  
Heating Temperature ◽  
Growth Time ◽  
Photovoltaic Devices ◽  
X Ray Diffraction ◽  
Facile Synthesis ◽  
X Ray ◽  
Transmission Electron ◽  
20 Nm ◽  
Pbs Quantum Dots

Lead sulfide ( PbS ) quantum dots (QDs) capped with oleic acid and oleic amine were synthesized by using safe and innocuous sulfur powder as S source instead of the bis (trimethylsilyl) sulfide ((TMS)2S). QDs with size distribution from 20 nm to 3 nm were gained by controlling the experiment parameters such as heating temperature, capping agents and the growth time. The morphology and crystal structure of the as-prepared PbS QDs were characterized by (high-resolution) transmission electron microscopy (HR-TEM) images and powder X-ray diffraction (XRD). This method may offer a new route to synthesize PbS QDs for photovoltaic devices.

scholarly journals Synthesis of a thermoresponsive crosslinked MEO2MA polymer coating on microclusters of iron oxide nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alejandro Lapresta-Fernández ◽  
Alfonso Salinas-Castillo ◽  
Luis Fermín Capitán-Vallvey
Keyword(s):  
Iron Oxide ◽  
Synthesis Temperature ◽  
Water Soluble ◽  
Covalent Attachment ◽  
Solution Temperature ◽  
Tetraethylene Glycol ◽  
Critical Solution Temperature ◽  
Large Size ◽  
Transmission Electron ◽  
Azo Initiator

AbstractEncapsulation of magnetic nanoparticles (MNPs) of iron (II, III) oxide (Fe3O4) with a thermopolymeric shell of a crosslinked poly(2-(2-methoxyethoxy)ethyl methacrylate) P(MEO2MA) is successfully developed. Magnetic aggregates of large size, around 150–200 nm are obtained during the functionalization of the iron oxide NPs with vinyl groups by using 3-butenoic acid in the presence of a water soluble azo-initiator and a surfactant, at 70 °C. These polymerizable groups provide a covalent attachment of the P(MEO2MA) shell on the surface of the MNPs while a crosslinked network is achieved by including tetraethylene glycol dimethacrylate in the precipitation polymerization synthesis. Temperature control is used to modulate the swelling-to-collapse transition volume until a maximum of around 21:1 ratio between the expanded: shrunk states (from 364 to 144 nm in diameter) between 9 and 49 °C. The hybrid Fe3O4@P(MEO2MA) microgel exhibits a lower critical solution temperature of 21.9 °C below the corresponding value for P(MEO2MA) (bulk, 26 °C). The MEO2MA coating performance in the hybrid microgel is characterized by dynamic light scattering and transmission electron microscopy. The content of preformed MNPs [up to 30.2 (wt%) vs. microgel] was established by thermogravimetric analysis while magnetic properties by vibrating sample magnetometry.

Optical bistability induced by spin–orbit coupling in the carbon-nanotube quantum dots

2016 ◽  
Vol 55 (5) ◽  
pp. 1090 ◽  
Author(s):  
Wei Liu ◽  
Hongjun Zhang ◽  
Hui Sun ◽  
Qiaolin Zhang ◽  
Dandan Wang
Keyword(s):  
Quantum Dots ◽  
Carbon Nanotube ◽  
Optical Bistability ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit

Carbon nitride quantum dots tethered on CNTs for the electrochemical detection of dopamine and uric acid

2021 ◽  
Vol 45 (14) ◽  
pp. 6263-6272
Author(s):  
Biyas Posha ◽  
Narayanan Asha ◽  
N. Sandhyarani
Keyword(s):  
Quantum Dots ◽  
Uric Acid ◽  
Carbon Nanotube ◽  
Electrochemical Detection ◽  
Carbon Nitride ◽  
Multiwalled Carbon Nanotube ◽  
Multiwalled Carbon

A 0D–1D CNQDs/f-CNT architecture composed of 0D CNQDs tethered on a 1D functionalized multiwalled carbon nanotube (f-CNT) network was used for dopamine sensing.

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.

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