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cadmium-telluride
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Synthesis of CdTe Quantum Dots for Light Emitting Diodes and Chemical Sensing Applications
, Ph.D. Dissertation Sharif University of Technology ; Akhavan, Omid (Supervisor) ; Taghavinia, Nima (Supervisor)
Abstract
Luminescent semiconductor nanocrystals otherwise known as quantum dots (QDs) have attracted intense interest over the past decade due to their unique properties and great potential in various applications. In this work we have studied the growth and luminescence properties of CdTe QDs and CdTe/CdS core-shell QDs and their application in hybrid organic/inorganic light-emitting diodes (LEDs) and fluorescent sensors. CdTe QDs were synthesized using a thermochemical method in aqueous phase. Central composite design (CCD) was applied to obtain the optimized conditions of the synthesis. The effects of four independent parameters including molar ratios of Cd to Te ions, TGA to Te ions, pH of the...
Synthesis and Characterization of Nanostructured Cadmium Tellurides for Solar Cell Application
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Mohammad Reza (Supervisor)
Abstract
Recently, synthesis of nanostructured CdTe of II-VI semiconductors has caused much attention due to their great potential in many optoelectronic applications such as solar cells and detectors. Among different synthesis methods, solvothermal process is a suitable method due to low temperature synthesis. In this work CdTe nanoparticles, nanowires, nanorods and nanobelts with cubic structure (zincblende) were synthesized via a simple solvothermal method at a moderate temprature. The effect of processing parameters on some properties sush as crystal structure, morphology, crystallite size chemical bond configuration and optical properties of synthesized CdTe were investigated. It was found that,...
Detection of L-Dopa Based on Fluorescent of levodopa Nanopolymers and CdTe Quantum Dots
, M.Sc. Thesis Sharif University of Technology ; Hormozi Nezhad, Mohammad Reza (Supervisor)
Abstract
Levodopa [L-3, 4-dihydroxyphenylalanine, or L-DOPA] is an important neurotransmitter used for the treatment of neural disorders such as Parkinson’s disease. Abnormal L-Dopa concentrations in biological fluids can be used for evaluation of diseases such as Parkinson’s diseases. In the first part of this thesis, a rapid and sensitive method for levodopa detection was reported which is based on in situ formation of polylevodopa nanoparticles. The assay is very simple and low cost and uses only NaOH and HCl as reagents. Under alkaline conditions, levodopa is spontaneously oxidized to its quinone derivative and shows the fluorescence properties. The fluorescence signal of the oxidation product of...
Preparation of Tthin Film CdS/CdTe Solar Cells: Containing CdS Nanowires and CdTe Particles
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Mohammad Reza (Supervisor)
Abstract
In the present work, we have designed a novel CdS/CdTe solar cell based on CdS nanowires, as a window layer, and CdTe nanoparticles, as a absorber layer. CdS nanowires and CdTe nanoparticles were synthesized by solvothermal method. The samples were characterized by X-ray diffraction diffractometer (XRD), field emission scanning electron microscope (FE-SEM), Atomic Force Microscope (AFM) and Ultraviolet–Visible (UV–vis) spectroscopy spectrometer. Photocurrent measurements were carried out using a 150 W xenon lamp with an air-mass (AM) 1.5 filter. The performance of the solar cell based on the CdS nanowire (NW-CdS) film with 225 nm thickness and CdTe nanoparticle (NP-CdTe) film with 6 μm...
Effect of hydrazine hydrate on the luminescence properties of MPA capped CdTe nanocrystals in hot injection method
, Article Journal of Luminescence ; Vol. 156, issue , 2014 , p. 235-239 ; Marandi, M ; Zare Bidaki, H ; Sharif University of Technology
Abstract
In this research MPA capped CdTe nanocrystals with sizes around 2.7-3.5 nm were grown in aqueous solution. The process was performed through the reaction of NaHTe with MPA and CdCl2 solution in high temperature. The synthesis was carried out in two different states of standard and modified forms. In the modified synthesis, the hydrazine hydrate material was added to the MPA plus CdCl2 solution before injection. The evolution of the nanocrystals size and PL quantum yield was monitored during the heating time for the growth. The results demonstrated that for the standard synthesis the growth rate was slow. The CdTe nanocrystals with high PL quantum yields were achieved in more than 10 h of...
Influence of heavy nanocrystals on spermatozoa and fertility of mammals
, Article Materials Science and Engineering C ; Volume 69 , 2016 , Pages 52-59 ; 09284931 (ISSN) ; Hashemi, E ; Zare, H ; Shamsara, M ; Taghavinia, N ; Heidari, F ; Sharif University of Technology
Elsevier Ltd
Abstract
In recent years, quantum dots (QDs) have been widely used in upcoming nanotechnology-based solar cells, light-emitting diodes and even bioimaging, due to their tunable optical properties and excellent quantum yields. But, such nanostructures are currently constituted by heavy elements which can threat the human health and living environment. Hence, in this work, the in vivo effects of CdTe nanocrystals (NCs) (as one of the promising QDs) on spermatozoa of male mice and subsequently on fertility of female mice were investigated, for the first time. To do this, CdTe NCs were synthesized through an environment-friendly (aqueous-based solution) method. The sperm cells presented a high potential...
Novel aspects of application of cadmium telluride quantum dots nanostructures in radiation oncology
, Article Applied Physics A: Materials Science and Processing ; Volume 123, Issue 8 , 2017 ; 09478396 (ISSN) ; Zare, H ; Karimi, S ; Rahighi, R ; Feizi, S ; Sharif University of Technology
Springer Verlag
2017
Abstract
In the last two decades, quantum dots nanomaterials have garnered a great deal of scientific interest because of their unique properties. Quantum dots (QDs) are inorganic fluorescent nanocrystals in the size range between 1 and 20 nm. Due to their structural properties, they possess distinctive properties and behave in different way from crystals in macro scale, in many branches of human life. Cadmium telluride quantum dots (CdTe QDs) were labeled with 68Ga radio nuclide for fast in vivo targeting and coincidence imaging of tumors. Using instant paper chromatography, the physicochemical properties of the Cadmium telluride quantum dots labeled with 68Ga NPs (68Ga@ CdTe QDs) were found high...
Design of a ratiometric fluorescent probe for naked eye detection of dopamine
, Article Analytical Methods ; Volume 9, Issue 23 , 2017 , Pages 3505-3512 ; 17599660 (ISSN) ; Hormozi Nezhad, M. R ; Sharif University of Technology
Abstract
A simple and effective ratiometric fluorescence sensor for selective detection of dopamine (DA) in alkaline media has been developed by simply mixing thioglycolic acid (TGA) functionalized orange fluorescent cadmium telluride (CdTe) quantum dots (QDs) with amino-functionalized blue fluorescent carbon nanodots (CDs). Under a single excitation wavelength of 365 nm, the sensor exhibits dual-emissions centered at 445 and 603 nm. The fluorescence of CdTe QDs is selectively quenched by DA, whereas the fluorescence of CDs is insensitive to the analyte. In the presence of different amounts of DA, the variations in the dual emission intensity ratios exhibit a continuous color change from pink to...
A smart-phone based ratiometric nanoprobe for label-free detection of methyl parathion
, Article Sensors and Actuators, B: Chemical ; Volume 322 , 2020 ; Hormozi Nezhad, M. R ; Sharif University of Technology
Elsevier B.V
2020
Abstract
The widespread use of pesticides in pest management has boosted the demands for developing highly sensitive probes for on-site monitoring. Herein we presented a sensitive enzyme-free ratiometric probe for determination of methyl parathion (MP), as an organophosphate pesticide using TGA-capped CdTe QDs and carbon dots (CDs). Unlike previous methods in which hydrolysis product of MP is instrumental in the response of the sensors, here, self-assembly of cetyltrimethylammonium bromide (CTAB) on the surface of non-modified yellow-emissive CdTe QDs facilitates the quenching of CTAB-QDs upon addition of MP while the fluorescence intensity of CDs remains constant. Using a smartphone, the ratiometric...
Visual recognition of tryptophan enantiomers using chiral self assemblies of quantum dots
, Article ACS Applied Nano Materials ; 2021 ; 25740970 (ISSN) ; Jafar Nezhad Ivrigh, Z ; Bigdeli, A ; Hormozi Nezhad, M.R ; Sharif University of Technology
American Chemical Society
2021
Abstract
Discrimination of chiral targets is generally achieved with chiral nanomaterials. However, the limited number of intrinsic chiral nanostructures as well as their complex synthesis procedure has led to the production of chirality-induced nanomaterials as alternatives. Chirality can be induced in nanomaterials by either chirality transfer or the formation of chiral assemblies. Using the latter approach, in this work, we have provided chiral supramolecular assemblies of CdTe quantum dots (QDs) from achiral starting materials. CTAB-QD assemblies showed chiroptical activities, and their orange emission in combination with the blue emission of carbon dots was utilized as a ratiometric chiral...
Visual recognition of tryptophan enantiomers using chiral self assemblies of quantum DOTS
, Article ACS Applied Nano Materials ; Volume 5, Issue 1 , 2022 , Pages 1460-1471 ; 25740970 (ISSN) ; Jafar Nezhad Ivrigh, Z ; Bigdeli, A ; Hormozi Nezhad, M. R ; Sharif University of Technology
American Chemical Society
2022
Abstract
Discrimination of chiral targets is generally achieved with chiral nanomaterials. However, the limited number of intrinsic chiral nanostructures as well as their complex synthesis procedure has led to the production of chirality-induced nanomaterials as alternatives. Chirality can be induced in nanomaterials by either chirality transfer or the formation of chiral assemblies. Using the latter approach, in this work, we have provided chiral supramolecular assemblies of CdTe quantum dots (QDs) from achiral starting materials. CTAB-QD assemblies showed chiroptical activities, and their orange emission in combination with the blue emission of carbon dots was utilized as a ratiometric chiral...
Identification of catecholamine neurotransmitters using fluorescence sensor array
, Article Analytica Chimica Acta ; Volume 917 , 2016 , Pages 85-92 ; 00032670 (ISSN) ; Hormozi Nezhad, M. R ; Mahmoudi, M ; Sharif University of Technology
Elsevier B.V
2016
Abstract
A nano-based sensor array has been developed for identification and discrimination of catecholamine neurotransmitters based on optical properties of their oxidation products under alkaline conditions. To produce distinct fluorescence response patterns for individual catecholamine, quenching of thioglycolic acid functionalized cadmium telluride (CdTe) quantum dots, by oxidation products, were employed along with the variation of fluorescence spectra of oxidation products. The spectral changes were analyzed with hierarchical cluster analysis (HCA) and principal component analysis (PCA) to identify catecholamine patterns. The proposed sensor could efficiently discriminate the individual...
Cadmium telluride quantum dots induce apoptosis in human breast cancer cell lines
, Article Toxicology and Industrial Health ; Volume 34, Issue 5 , 2018 , Pages 339-352 ; 07482337 (ISSN) ; Zare, H ; Taghavinia, N ; Irajizad, A ; Aghaei, M ; Panjehpour, M ; Sharif University of Technology
SAGE Publications Ltd
2018
Abstract
Introduction: Semiconductor quantum dots (QDs), especially those containing cadmium, have undergone marked improvements and are now widely used nanomaterials in applicable biological fields. However, great concerns exist regarding their toxicity in biomedical applications. Because of the lack of sufficient data regarding the toxicity mechanism of QDs, this study aimed to evaluate the cytotoxicity of three types of QDs: CdTe QDs, high yield CdTe QDs, and CdTe/CdS core/shell QDs on two human breast cancer cell lines MDA-MB468 and MCF-7. Methods: The breast cancer cells were treated with different concentrations of QDs, and cell viability was evaluated via MTT assay. Hoechst staining was...
Radial basis function-artificial neural network (RBF-ANN) for simultaneous fluorescent determination of cysteine enantiomers in mixtures
, Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 261 , 2021 ; 13861425 (ISSN) ; Reza Hormozi Nezhad, M ; Abdollahi, H ; Sharif University of Technology
Elsevier B.V
2021
Abstract
The determination of chiral compounds is critically important in chemical and pharmaceutical sciences. Cysteine amino acid is one of the important chiral compounds where each enantiomer (L and D) has different effects on fundamental physiological processes. The unique optical properties of nanoparticles make them a suitable probe for the determination of different analytes. In this work, the water-soluble thioglycolic acid (TGA)-capped cadmium-telluride (CdTe) quantum dots (QDs) were applied as optical nanoprobe for the simultaneous determination of cysteine enantiomers. The difference in the kinetics of the interactions between L- and D-cysteine with CdTe QDs is used for multivariate...
Fabrication and Characterization of Cu2SnS3 and Cu2ZnSnS(e)4 Absorber Layers by Spray Pyrolysis Method
, M.Sc. Thesis Sharif University of Technology ; Mahdavi, Mohammad (Supervisor)
Abstract
The Cu2ZnSnS(e)4 (CZTS(e)) quaternary and Cu2SnS3 (CTS) ternary componds with suitable optical and electrical properties have been considered as an emerging semiconductors for fabrication of thin-fim solar cells. So far, two technologies based on CdTe and CuInGaS(e)2 absorbers have achived efficiencies above 20%. However, these compounds contain toxic element Cd and rare elements such as In and Ga which, limited the development of these solar cells.In this research a 3-stage method was used for fabrication of CZTS(e) thin Films. In the first stage, CTS layers were deposited by spray pyrolysis method, in the second one, ZnS layers were also deposited on CTS layers by spray pyrolysis method...
Dependence of photovoltaic performance of solvothermally prepared CdS/CdTe solar cells on morphology and thickness of window and absorber layers
, Article Journal of Materials Science: Materials in Electronics ; Volume 24, Issue 9 , 2013 , Pages 3564-3574 ; 09574522 (ISSN) ; Mohammadi, M. R ; Sharif University of Technology
2013
Abstract
In the present work a new strategy for straightforward fabrication of CdS/CdTe solar cells, containing CdS nanowires and nanoparticles as a window layer and CdTe nanoparticles and microparticles as an absorber layer, are reported. CdS and CdTe nanostructures were synthesized by solvothermal method. X-ray diffraction analysis revealed that highly pure and crystallized CdS nanowires and nanoparticles with hexagonal structure and CdTe nanoparticles with cubic structure were obtained. Atomic force microscope and field emission scanning electron microscope images showed that CdS nanowires with length of several μm and average diameter of 35 nm, CdS nanoparticles with average particle size of 32...
Identification of catecholamine neurotransmitters using fluorescence sensor array
, Article Analytica Chimica Acta ; Volume 917 , April , 2016 , Pages 85–92 ; 00032670 (ISSN) ; Hormozi Nezhad, M. R ; Mahmoudi, M ; Sharif University of Technology
Elsevier
2016
Abstract
A nano-based sensor array has been developed for identification and discrimination of catecholamine neurotransmitters based on optical properties of their oxidation products under alkaline conditions. To produce distinct fluorescence response patterns for individual catecholamine, quenching of thioglycolic acid functionalized cadmium telluride (CdTe) quantum dots, by oxidation products, were employed along with the variation of fluorescence spectra of oxidation products. The spectral changes were analyzed with hierarchical cluster analysis (HCA) and principal component analysis (PCA) to identify catecholamine patterns. The proposed sensor could efficiently discriminate the individual...
Highly sensitive selective sensing of nickel ions using repeatable fluorescence quenching-emerging of the CdTe quantum dots
, Article Materials Research Bulletin ; Volume 95 , 2017 , Pages 532-538 ; 00255408 (ISSN) ; Ghalkhani, M ; Akhavan, O ; Taghavinia, N ; Marandi, M ; Sharif University of Technology
Abstract
Highly sensitive nickel sensor based on repeatable fluorescence quenching-emerging mechanism was developed. Highly luminescent thioglycolic acid capped CdTe nanocrystals in aqueous solution were applied as the fluorescence probe. These nanocrystals represented a considerable photoluminescence quantum yield as high as 61%. The florescence was quenched by addition of Ni ions to the CdTe nanocrystals solution. Then it was recovered by injection of the proper amount of dimethylglyoxime as the releasing reagent. The relative fluorescence intensity (F0/F) was linearly proportional to the concentration of nickel ions in the range of 0.01–10 μM, with detection limit as low as 7 nM. Described method...
Modeling the detection efficiency in photodetectors with temperature-dependent mobility and carrier lifetime
, Article Superlattices and Microstructures ; Volume 122 , 2018 , Pages 557-562 ; 07496036 (ISSN) ; Ahmadpour, M ; Mosavi, A ; Alharbi, N ; Gorji, N. E ; Sharif University of Technology
Abstract
We proposed a modeling procedure to calculate the impact of temperature on the detection efficiency in photodetectors based on CdTe materials. Temperature increase impacts on the electrical properties of the materials such as carrier mobility and carrier recombination lifetime. This impact which can be effective in some cases has been normally ignored in the modeling approaches presented in the literature. Here we show that increasing the temperature from 190 K to 300 K not reduces the mobility of both electrons and holes but also significantly reduces the carrier lifetime. The result will impact on electric-field within the depletion width of the device, drift and diffusion lengths which...
A new strategy to design colorful ratiometric probes and its application to fluorescent detection of Hg(II)
, Article Sensors and Actuators, B: Chemical ; Volume 259 , 2018 , Pages 894-899 ; 09254005 (ISSN) ; Hormozi Nezhad, M. R ; Mahmoudi, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
A new strategy has been proposed to expand color-tunability of ratiometric fluorescent probes. It was shown that the combination of blue emissive color (as an internal standard) and yellow emissive color (as a probe) is an efficient way to create an extensive color range in ratiometric probes. However, due to the nature of the interaction between the analyte and the probe in terms of fluorescence quenching, occurance of the redshift in the emission is the major provision of such a probe. Our developed ratiometric fluorescence probe consists of blue emissive carbon dots (BCDs) and thioglycolic acid (TGA)-capped yellow emissive cadmium telluride (CdTe) quantum dots (YQDs). The ratiometric...