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Nanomaterials
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Preparation, Characterization and Utility of Quantum Dots
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Preparation, Characterization and Utility of Quantum Dots

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (31 May 2019) | Viewed by 18330

Special Issue Editor

Prof. Dr. Pavel Kopel

E-Mail Website
Guest Editor
Department of Inorganic Chemistry, Faculty of Science, Palacky University, CZ-771 46 Olomouc, Czech Republic
Interests: nanoparticles; materials chemistry; liposomes; bioinorganic chemistry; coordination chemistry; controlled drug delivery; carbon nanomaterials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

There is considerable interest in the preparation and study of quantum dots (QDs). Semiconductor quantum dots (QD) have been applied, for example, as labels in bioimaging and biosensing. Many QDs contained cadmium and telluride, and, although these achieved very high photoluminescence quantum yield (PL QY) and tunability of emission color, their toxicities have to be considered. Nowadays, researchers are more focused on the preparation and application of core/shell or cadmium-free quantum dots. Carbon quantum dots (CQDs) are a relatively new class of nanomaterials that have attracted a great deal of attention as promising substitutes to already-available semiconductor QDs, owing to their unique properties and non-toxicity. Surface passivation and functionalization play very important roles in the properties and utilization of prepared QDs.

In this Special Issue, we are especially interested in papers based on all aspects connected with QD syntheses, optical imaging, biosensing, immunosensing, optical tracking, drug delivery, protein/peptide delivery, and diagnostics. In vitro and in vivo toxicity studies are welcomed, as well as other fields of QDs applications, such as optoelectronics, photovoltaics and photocatalysis.

Dr. Pavel Kopel
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Quantum dots
  • Bioimaging
  • Biosensing
  • Biocompatibility
  • Drug and peptide delivery
  • Quantum dots utility

Published Papers (5 papers)

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Research

9 pages, 2149 KiB  
Article
Uncooled Short-Wave Infrared Sensor Based on PbS Quantum Dots Using ZnO NPs
by JinBeom Kwon, SaeWan Kim, JaeSung Lee, CheolEon Park, OkSik Kim, Binrui Xu, JinHyuk Bae and ShinWon Kang
Nanomaterials 2019, 9(7), 926; https://doi.org/10.3390/nano9070926 - 27 Jun 2019
Cited by 17 | Viewed by 3817
Abstract
Shortwave infrared (SWIR) sensors have attracted interest due to their usefulness in applications like military and medical equipment. SWIR sensors based on various materials are currently being studied. However, most SWIR detectors need additional optical filters and cooling systems to detect specific wavelengths. [...] Read more.
Shortwave infrared (SWIR) sensors have attracted interest due to their usefulness in applications like military and medical equipment. SWIR sensors based on various materials are currently being studied. However, most SWIR detectors need additional optical filters and cooling systems to detect specific wavelengths. In order to overcome these limitations, we proposed a solution processed SWIR sensor that can operate at room temperature using lead chloride (PbS) QDs as a photoactive layer. Additionally, we adapted zinc oxide (ZnO) nanoparticles (NPs) as an electron transport layer (ETL) to improve the sensitivity of a PbS SWIR sensor. In this study, PbS SWIR sensors with and without a ZnO NPs layer were fabricated and their current–voltage (I–V) characteristics were measured. The on/off ratio of the PbS SWIR sensor with ZnO NPs was 2.87 times higher than that of the PbS SWIR sensor without ZnO NPs at the maximum current difference. The PbS SWIR sensor with ZnO NPs showed more stable current characteristics than that without ZnO NPs because of the ZnO NPs’ high electron mobility and proper lowest unoccupied molecular orbital (LUMO) level. Full article
(This article belongs to the Special Issue Preparation, Characterization and Utility of Quantum Dots)
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18 pages, 3894 KiB  
Article
Negative Differential Conductance Assisted by Optical Fields in a Single Quantum Dot with Ferromagnetic Electrodes
by Weici Liu, Faqiang Wang, Zhilie Tang and Ruisheng Liang
Nanomaterials 2019, 9(6), 863; https://doi.org/10.3390/nano9060863 - 06 Jun 2019
Cited by 4 | Viewed by 2216
Abstract
In a single quantum dot (QD) system connected with ferromagnetic electrodes, the electron transport properties, assisted by the thermal and Fock state optical fields, are theoretically studied by the Keldysh nonequilibrium Green’s function approach. The results show that the evolution properties of the [...] Read more.
In a single quantum dot (QD) system connected with ferromagnetic electrodes, the electron transport properties, assisted by the thermal and Fock state optical fields, are theoretically studied by the Keldysh nonequilibrium Green’s function approach. The results show that the evolution properties of the density of state and tunneling current assisted by the Fock state optical field, are quite different from those of the thermal state. The photon sideband shift decreases monotonously with the increase in the electron–photon coupling strength for the case of the thermal state, while the shift is oscillatory for the case of the Fock state. Negative differential conductance (NDC) appears obviously in a QD system contacted with parallel (P) and antiparallel (AP) magnetization alignment of the ferromagnetic electrode leads, assisted by the Fock state optical field in a wide range of electron–photon interaction parameters. Evident NDC usually only arises in an AP configuration QD system assisted by the thermal state optical field. The results have the potential to introduce a new way to actively manipulate and control the single-electron tunneling transport on a QD system by the quantum states of the optical field. Full article
(This article belongs to the Special Issue Preparation, Characterization and Utility of Quantum Dots)
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12 pages, 2486 KiB  
Article
Plasmon-Enhanced Blue-Light Emission of Stable Perovskite Quantum Dot Membranes
by Kai Gu, Hongshang Peng, Siwei Hua, Yusong Qu and Di Yang
Nanomaterials 2019, 9(5), 770; https://doi.org/10.3390/nano9050770 - 19 May 2019
Cited by 7 | Viewed by 3723
Abstract
A series of stable and color-tunable MAPbBr3−xClx quantum dot membranes were fabricated via a cost-efficient high-throughput technology. MAPbBr3−xClx quantum dots grown in-situ in polyvinylidene fluoride electrospun nanofibers exhibit extraordinary stability. As polyvinylidene fluoride can prevent the molecular [...] Read more.
A series of stable and color-tunable MAPbBr3−xClx quantum dot membranes were fabricated via a cost-efficient high-throughput technology. MAPbBr3−xClx quantum dots grown in-situ in polyvinylidene fluoride electrospun nanofibers exhibit extraordinary stability. As polyvinylidene fluoride can prevent the molecular group MA+ from aggregating, MAPbBr3−xClx quantum dots are several nanometers and monodisperse in polyvinylidene fluoride fiber. As-prepared MAPbBr3−xClx quantum dot membranes exhibit the variable luminous color by controlling the Cl− content of MAPbBr3−xClx quantum dots. To improve blue-light emission efficiency, we successfully introduced Ag nanoparticle nanofibers into MAPbBr1.2Cl1.8 quantum dot membranes via layer-by-layer electrospinning and obtained ~4.8 folds fluorescence enhancement for one unit. Furthermore, the originality explanation for the fluorescence enhancement of MAPbBr3−xClx quantum dots is proposed based on simulating optical field distribution of the research system. Full article
(This article belongs to the Special Issue Preparation, Characterization and Utility of Quantum Dots)
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10 pages, 4248 KiB  
Article
Preparation of Tin Oxide Quantum Dots in Aqueous Solution and Applications in Semiconductor Gas Sensors
by Jianqiao Liu, Weiting Xue, Guohua Jin, Zhaoxia Zhai, Jiarong Lv, Wusong Hong and Yuzhen Chen
Nanomaterials 2019, 9(2), 240; https://doi.org/10.3390/nano9020240 - 11 Feb 2019
Cited by 25 | Viewed by 3923
Abstract
Tin oxide quantum dots (QDs) were prepared in aqueous solution from the precursor of tin dichloride via a simple process of hydrolysis and oxidation. The average grain size of QDs was 1.9 nm. The hydrothermal treatment was used to control the average grain [...] Read more.
Tin oxide quantum dots (QDs) were prepared in aqueous solution from the precursor of tin dichloride via a simple process of hydrolysis and oxidation. The average grain size of QDs was 1.9 nm. The hydrothermal treatment was used to control the average grain size, which increased to 2.7 and 4.0 nm when the operating temperatures of 125 and 225 °C were employed, respectively. The X-ray photoelectron spectroscopy (XPS) spectrum and X-ray diffraction analysis (XRD) pattern confirmed a rutile SnO2 system for the QDs. A band gap of 3.66 eV was evaluated from the UV-VIS absorption spectrum. A fluorescence emission peak was observed at a wavelength of 300 nm, and the response was quenched by the high concentration of QDs in the aqueous solution. The current-voltage (I-V) correlation inferred that grain boundaries had the electrical characteristics of the Schottky barrier. The response of the QD thin film to H2 gas revealed its potential application in semiconductor gas sensors. Full article
(This article belongs to the Special Issue Preparation, Characterization and Utility of Quantum Dots)
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9 pages, 1849 KiB  
Short Note
Time-Dependent Growth of Silica Shells on CdTe Quantum Dots
by Pavlína Modlitbová, Karel Klepárník, Zdeněk Farka, Pavel Pořízka, Petr Skládal, Karel Novotný and Jozef Kaiser
Nanomaterials 2018, 8(6), 439; https://doi.org/10.3390/nano8060439 - 16 Jun 2018
Cited by 8 | Viewed by 3986
Abstract
The purpose of this study is to investigate the time dependent growth of silica shells on CdTe quantum dots to get their optimum thicknesses for practical applications. The core/shell structured silica-coated CdTe quantum dots (CdTe/SiO2 QDs) were synthesized by the Ströber process, [...] Read more.
The purpose of this study is to investigate the time dependent growth of silica shells on CdTe quantum dots to get their optimum thicknesses for practical applications. The core/shell structured silica-coated CdTe quantum dots (CdTe/SiO2 QDs) were synthesized by the Ströber process, which used CdTe QDs co-stabilized by mercaptopropionic acid. The coating procedure used silane primer (3-mercaptopropyltrimethoxysilane) in order to make the quantum dots (QDs) surface vitreophilic. The total size of QDs was dependent on both the time of silica shell growth in the presence of sodium silicate, and on the presence of ethanol during this growth. The size of particles was monitored during the first 72 h using two principally different methods: Dynamic Light Scattering (DLS), and Scanning Electron Microscopy (SEM). The data obtained by both methods were compared and reasons for differences discussed. Without ethanol precipitation, the silica shell thickness grew slowly and increased the nanoparticle total size from approximately 23 nm up to almost 30 nm (DLS data), and up to almost 60 nm (SEM data) in three days. During the same time period but in the presence of ethanol, the size of CdTe/SiO2 QDs increased more significantly: up to 115 nm (DLS data) and up to 83 nm (SEM data). The variances occurring between silica shell thicknesses caused by different methods of silica growth, as well as by different evaluation methods, were discussed. Full article
(This article belongs to the Special Issue Preparation, Characterization and Utility of Quantum Dots)
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