Download or read book SYNTHESIS AND BIOLOGICAL APPLICATIONS OF HEAVY METAL FREE SEMICONDUCTOR NANOCRYSTALS written by Ying Qi and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor nanocrystals, also called quantum dots (QDs), are an interesting class of materials exhibiting size-tunable optical properties. QDs are attractive for a variety of applications, such as biological sensing and imaging, high color definition display technologies, and photovoltaics. The most widely studied QDs are compound semiconductors of the type CdX and PbX (with X= S, Se, and Te). The absorption and fluorescence emission wavelengths of these QDs span the visible and near infrared (NIR) regions of the electromagnetic spectrum. However, the highly toxic heavy metals Cd and Pb contained in these materials are problematic for their widespread use in commercial applications. Substitution of the heavy metals with Zn and Sn can yield QDs that are less toxic and more environmentally friendly. ZnSe QDs are highly luminescent in the UV-blue region of the spectrum and can be engineered to emit at longer wavelengths by doping them with transition metals, such as Mn or Cu. Encapsulation of ZnSe QDs with an inorganic shell, such as ZnS, has been shown to increase their stability and fluorescence intensity (quantum yield). However, the thermodynamic stability of such core/shell particles must be studied to understand the feasibility and long-term stability of atomically-abrupt interfaces between the core and the shell. The thermodynamic stability of ZnSe/ZnTe and ZnTe/ZnSe core/shell QDs was explored in this study. It was found that ZnSe/ZnTe core/shell QDs are thermodynamically more stable than ZnTe/ZnSe core/shell QDs. Functionalization of the surface of the QDs with biomolecules enables their use in biological sensing and imaging applications. A ZnSe-based QD-DNA biosensor was fabricated and characterized using a novel portable time-domain LED fluorimeter that enables nanosecond fluorescence lifetime measurements. SnSe QDs that absorb near-infrared (NIR) radiation are attractive nano-materials for applications in photovoltaics, photodetectors and photothermal therapy. A new synthesis method for small-size (

Download or read book Colloidal Semiconductor Nanocrystals Synthesis Properties and Applications written by Vladimir Lesnyak and published by Frontiers Media SA. This book was released on 2020-01-06 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nanocrystals written by Sudheer Neralla and published by BoD – Books on Demand. This book was released on 2012-08-29 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanocrystals research has been an area of significant interest lately, due to the wide variety of potential applications in semiconductor, optical and biomedical fields. This book consists of a collection of research work on nanocrystals processing and characterization of their structural, optical, electronic, magnetic and mechanical properties. Various methods for nanocrystals synthesis are discussed in the book. Size-dependent properties such as quantum confinement, superparamagnetism have been observed in semiconductor and magnetic nanoparticles. Nanocrystals incorporated into different material systems have proven to possess improved properties. A review of the exciting outcomes nanoparticles study has provided indicates further accomplishments in the near future.

Download or read book Semiconductor and Metal Nanocrystals written by Victor I. Klimov and published by CRC Press. This book was released on 2003-11-07 with total page 479 pages. Available in PDF, EPUB and Kindle. Book excerpt: The vast technological potential of nanocrystalline materials, as well as current intense interest in the physics and chemistry of nanoscale phenomena, has led to explosive growth in research on semiconductor nanocrystals, also known as nanocrystal quantum dots, and metal nanoparticles. Semiconductor and Metal Nanocrystals addresses current topics impacting the field including synthesis and assembly of nanocrystals, theory and spectroscopy of interband and intraband optical transitions, single-nanocrystal optical and tunneling spectroscopies, electrical transport in nanocrystal assemblies, and physical and engineering aspects of nanocrystal-based devices. Written by experts who have contributed pioneering research, this reference comprises key advances in the field of semiconductor nanocrystal quantum dots and metal nanoparticles over the past several years. Focusing specifically on nanocrystals generated through chemical techniques, Semiconductor and Metal Nanocrystals Merges investigative frontiers in physics, chemistry, and engineering Documents advances in nanocrystal synthesis and assembly Explores the theory of electronic excitations in nanoscale particles Presents comprehensive information on optical spectroscopy of interband and intraband optical transitions Reviews data on single-nanocrystal optical and tunneling spectroscopies Weighs controversies related to carrier relaxation dynamics in ultrasmall nanoparticles Discusses charge carrier transport in nanocrystal assemblies Provides examples of lasing and photovoltaic nanocrystal-based devices Semiconductor and Metal Nanocrystals is a must read for scientists, engineers, and upper-level undergraduate and graduate students interested in the physics and chemistry of nanoscale semiconductor and metal particles, as well as general nanoscale science. About the Editor: VICTOR I. KLIMOV is Team Leader, Softmatter Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory, New Mexico. The recipient of the Los Alamos Fellows Prize (2000), he is a Fellow of the Alexander von Humboldt Foundation, leader of the Nanophotonics and Nanoelectronics Thrust of the Center for Integrated Nanotechnologies (U.S. Department of Energy), a member of the Los Alamos Board of Governors of the Institute for Complex Adaptive Matter, and a member of the Steering Committee for the Los Alamos Quantum Institute. He received the M.S. (1978), Ph.D. (1981), and Dr. Sci. (1993) degrees from Moscow State University, Russia.

Download or read book Semiconductor Nanocrystals written by Peter Matthew Allen and published by . This book was released on 2010 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary focus of this thesis is the synthesis and applications of semiconductor nanocrystals, or quantum dots (QDs). Novel synthetic routes to ternary 1-III-VI QDs are presented, and we report the first highly luminescent Cu-In-Se QDs spanning the red to near-infrared region. The synthetic method is modular and is extended to Ag-In-Se, Cu-In-Zn-S, and Ag-In-Zn-S QDs, luminescent from the blue to near-infrared. The development of new core-shell InAs(ZnCdS) QDs is discussed in the context of making highly fluorescent, stable biological probes in the near-infrared region. Applications in biological systems from cellular labeling to sentinel lymph node mapping are demonstrated. In addition, we present new methods for doping InAs QDs in order to control carrier type through the introduction of acceptor defects such as cadmium. The synthesis and characterization of n and p type InAs QDs is discussed. In order to understand the differences in size distributions with current III-V QD synthetic procedures and II-VI and IV-VI QD syntheses we have explored the molecular mechanisms that lead to the formation of InP and InAs QDs. We find that current III-V QD syntheses result in the depletion of molecular precursors immediately following nucleation, preventing growth from molecular precursors, thus failing to meet the a key criterion for a monodisperse colloidal synthesis in the Dinegar and LaMer model. In the conclusion of this thesis, we explore the electrically controlled solution-liquid-solid (EC-SLS) synthesis of InP nanowires. Using the EC-SLS method, we are able to controllably place n type InP nanowires into field effect transistor geometries.

Download or read book Metal and Semiconductor Nanocrystals written by Jing Zhao and published by Frontiers Media SA. This book was released on 2020-01-14 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study on the Synthesis and Characterization of Ternary Semiconductor Nanocrystals written by Tyler Hurlburt and published by . This book was released on 2013 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Applications of Semiconductor Nanostructures written by Karamjit Singh Dhaliwal and published by Bentham Science Publishers. This book was released on 2023-08-18 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthesis and Applications of Semiconductor Nanostructures consists of 15 chapters that focus on synthesis, characterization and multifaceted potential applications of semiconductor nanostructures, metal organic frameworks (MOFs) and nanostructure impregnated metal-organic frameworks (MOFs). Special materials included in the volume include doped glasses, functionalized carbon nanotubes, doped graphene and graphene nanoribbons. The contributions highlight numerous bottom-up and top-down techniques for the synthesis of semiconductor nanostructures. Several industrial processes such as hydrogen production, wastewater treatment, carbon dioxide reduction, pollution control and oxidation of alcohols have been demonstrated in the context of semiconductor nanomaterial applications. The volume also has chapters dedicated to updates on the biomedical applications of these nanomaterials. This volume is a timely resource for postgraduate students, academicians, researchers and technocrats, who are involved in R&D activities with semiconductor nanomaterials and metal organic frameworks.

Download or read book Photoactive Semiconductor Nanocrystal Quantum Dots written by Alberto Credi and published by Springer. This book was released on 2017-01-20 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.

Download or read book written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Property Characterization of Novel Ternary Semiconductor Nanomaterials written by Baodong Mao and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alloying and doping have been widely used for band gap engineering and property tuning of semiconductor nanocrystals, providing novel composition and structure dependent properties. Ternary I-III-VI semiconductors represent one of the best heavy-metal-free optoelectronic materials. Here, efforts are devoted to improving the optical and electrical properties of the semiconductor nanocrystals and photophysical studies of related mechanisms. AgInS2 nanocrystals with tunable sizes and optical properties were synthesized in toluene at low temperature. The role of surface and intrinsic defects were studied using time-resolved photoluminecence and femtosecond transient absorption spectroscopies. Extremely long-lived excitons were observed in the AgInS2 nanocrystals, which can benefit potential phototovoltaic applications by increasing charge separation. Series of AgInS2-ZnS nanocrystals were synthesized by heating a Ag/In/Zn/S solution showing tunable PL which initially exhibits a red shift but ultimately finishes with blue shifted emission with increasing temperature. The incorporation of Zn and the increased cation exchange of silver by zinc at higher temperatures strongly influences the PL behavior. Systematic investigation by time-resolved spectroscopy showed distinguishable PL behaviors between developing and fully grown AgInS2-ZnS nanocrystals. We also synthesized near-infrared emitting AgInS2/ZnS nanocrystals with a thin layer of ZnS by carefully controlling the growing condition. The unexpected PL red shift and band gap reduction was ascribed to the local structural ordering in the thin gradient alloyed surface layer. Zinc concentration and growth temperatures played important roles in the formation of the near-infrared emitting nanocrystals, which are promising for bioimaging applications. For the self-doped Cu2-xS nanocrystals, several methods were explored to tune the free carrier plasmon absorption properties, which showed dramatic change with the amount of hole doping resulted from copper deficiency. X-ray photoelectron spectroscopy was used to identify the copper oxidation stayes and the origin of the valence band vacancies. Detailed analysis suggested an interesting partially oxidized layer on the nanocrystal surface. The last section is devoted to improving the thermoelectric performance of nanostructured ternary Bi0̣5Sb1̣5Te3. Sintering was found to increase ZT as a function of sintering temperature by increasing the charge carrier mobility more than the lattice thermal conductivity, resulting in an overall increase of thermoelectric performance

Download or read book Nucleic Acids templated Semiconductor Nanocrystals written by Nan Ma and published by . This book was released on 2009 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor nanocrystals are used widely as biological labels and components of optoelectronic devices. The spectral tunability and stability of these materials makes them ideal building blocks and probes. This thesis describes work on a class of semiconductor nanocrystals with properties controlled by the structure and sequence of nucleic acids. Controlling nanocrystal properties using rationally designed nucleic acids structures and sequences presents a new means to engineer inorganic structures with desired properties, and provides a means to produce biofunctionalized imaging labels in a single step. The materials produced using this approach have favorable characteristics, including bright emission, high stability, and straightforward synthetic manipulation.The properties of semiconductor nanocrystals are known to be strongly dependent on the ligand used during synthesis that serves to passivate the surface. We endeavored to use a class of ligands that would have intrinsic self-assembly properties and inherent biocompatibility. We therefore tested nucleic acids including DNA and RNA molecules as ligands for cadmium and lead-based nanocrystals formation. Nucleic acids molecules passivate on semiconductor nanocrystal surface through their nucleobase functionalities as well as the phosphate backbone. Among the four natural mononucleotides, guanine is the most effective nucleotide for semiconductor nanocrystals formation. Semiconductor nanocrystals synthesized with different DNA homopolymer sequences possess distinct luminescence intensities. A general approach is being developed to systematically control semiconductor nanocrystals luminescence using rationally designed DNA sequences. In addition, the effect of nucleic acids structure on CdS semiconductor nanocrystals properties is elucidated using transfer RNA molecules as a ligand system, and differences in size and morphology were observed for the semiconductor nanocrystals synthesized with different RNA structures.DNA-passivated semiconductor nanocrystals exhibit low cytotoxicity and high stability in biological media and thus are superior for bioimaging applications. Given the molecular recognition properties of DNA and RNA aptamers with other biomolecules such as proteins or cell surface receptors, we were inspired to use a bi-functional DNA template to generate biofunctionalized semiconductor nanocrystals in a simple one-pot process. This novel strategy is realized by the design of a chimeric DNA template with a phosphorothioate domain for semiconductor nanocrystals passivation and a phosphate domain (aptamer) for biomolecule recognition. CdTe semiconductor nanocrystals synthesized with the chimeric DNA template possess high specificities towards the cognate DNA, protein, and cancer cell targets.

Download or read book Synthesis and Applications of Inorganic Nanostructures written by Huaqiang Cao and published by John Wiley & Sons. This book was released on 2017-09-27 with total page 720 pages. Available in PDF, EPUB and Kindle. Book excerpt: Authored by a leading figure in the field, this book systematically describes all the fundamental aspects and applications of inorganic nanostructures from zero to three dimensions. It not only discusses various synthesis technologies, but also covers the physical properties of inorganic nanostructures, such as optical, electric and magnetic properties, and practical applications such as energy storage (including Li-ion and Ni-MH batteries and supercapacitors), superhydrophobic and bio-applications, etc. The focus throughout is on the synthesis-structure-application relationships, including the growth mechanisms for the nanostrucutres. Concise yet comprehensive, this is indispensable reading for chemists and materials scientists.

Download or read book Silicon Nanocrystals written by Lorenzo Pavesi and published by John Wiley & Sons. This book was released on 2010-02-02 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique collection of knowledge represents a comprehensive treatment of the fundamental and practical consequences of size reduction in silicon crystals. This clearly structured reference introduces readers to the optical, electrical and thermal properties of silicon nanocrystals that arise from their greatly reduced dimensions. It covers their synthesis and characterization from both chemical and physical viewpoints, including ion implantation, colloidal synthesis and vapor deposition methods. A major part of the text is devoted to applications in microelectronics as well as photonics and nanobiotechnology, making this of great interest to the high-tech industry.

Download or read book SYNTHESIS AND APPLICATIONS OF HETEROSTRUCTURED SEMICONDUCTOR NANOCRYSTALS written by Elena Khon and published by . This book was released on 2013 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor nanocrystals (NCs) have been of great interest to researchers for several decades due to their unique optoelectronic properties. These nanoparticles are widely used for a variety of different applications. However, there are many unresolved issues that lower the efficiency and/or stability of devices which incorporate these NCs. Our research is dedicated to addressing these issues by identifying potential problems and resolving them, improving existing systems, generating new synthetic strategies, and/or building new devices. The general strategies for the synthesis of different nanocrystals were established in this work, one of which is the colloidal growth of gold domains onto CdS semiconductor nanocrystals. Control of shape and size was achieved simply by adjusting the temperature and the time of the reaction. Depending on the exact morphology of Au and CdS domains, fabricated nano-composites can undergo evaporation-induced self-assembly onto a substrate, which is very useful for building devices. CdS/Au heterostructures can assemble in two different ways: through end-to-end coupling of Au domains, resulting in the formation of one-dimensional chains; and via side-by-side packing of CdS nanorods, leading to the onset of two-dimensional superlattices. We investigated the nature of exciton-plasmon interactions in Au-tipped CdS nanorods using femtosecond transient absorption spectroscopy. The study demonstrated that the key optoelectronic properties of electrically coupled metal and semiconductor domains are significantly different from those observed in systems with weak inter-domain coupling. In particular, strongly-coupled nanocomposites promote mixing of electronic states at semiconductor-metal domain interfaces, which causes a significant suppression of both plasmon and exciton carrier excitations. Colloidal QDs are starting to replace organic molecules in many different applications, such as organic light emmiting diods (OLEDs), due to their light emmision tunability. We reported a general strategy for the assembly of all-inorganic light-emitting nanocrystal films with an emission quantum yield in the 30-52% range. Our methodology relies on solution-processing of CdSe nanocrystals into a crystalline matrix of a wide band gap semiconductor (CdS, ZnS). As a result, we replace original organic ligands on nanocrystal surfaces with an inorganic medium which efficiently preserves the quantum confinement of electrical charges in CdSe NCs. In addition to strong emission, fabricated films demonstrated excellent thermal and chemical stability, and a large refractive index, which avails their integration into emerging solid-state nanocrystal devices. The ability to control size and shape of NCs is essential as it automatically affects the optoelectronic properties of the crystals. Colloidal chemistry offers an assortment of synthetic tools for tuning the shape of NCs, but some nanoparticle morphologies require alternative processing strategies. We have shown that chemical etching of colloidal nanoparticles can facilitate the realization of desirable nanocrystal geometries. This methodology allows both CdSe and CdS composed semiconductor domains be exposed to the external environment, while maintaining a structural design that is highly desirable for catalytic applications. Hydrogen production tests confirmed the improved catalytic activity of CdSe/CdS dimers. We expect that the demonstrated application will become a common methodology in the synthesis of charge-separating nanocrystals, leading to advanced nanoparticle architectures for applications in the areas of photocatalysis, photovoltaics, and light detection.

Download or read book Synthesis of Derivatizable Semiconductor Nanocrystals Through Rational Ligand Design and Applications Thereof written by José Manuel Cordero Hernández and published by . This book was released on 2016 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decade, the synthesis methods of colloidal nanocrystals have advanced at an astonishing rate, producing particles that are chemically stable, monodisperse, and, in the case of semiconductor quantum dots (QDs), immensely bright. Inorganic nanocrystals linked to functional organic or biological molecules have recently emerged as a new class of nanomaterials for generating highly efficient devices, and sensing agents for a broad range of advanced applications. A key step in the synthesis of these constructs involves transforming the chemistry of the surface from that generated by the nanocrystals synthesis conditions (high boiling-point and hydrophobic solvent environment) to one possessesing the appropriate functional groups for derivatization and that is compatible with the intended final application. Here, we describe the synthesis of a series of organic ligands that modify the surface in that manner. The first ligand exhibits a norbornene functional group and binds strongly to the surface of colloidal nanocrystallites during particle synthesis, eliminating the need for ligand exchange and enabling large-scale production of high quality derivatizable nanomaterials. This ligand is compatible with state-of-the-art synthesis methods of a large variety of semiconductor nanocrystallites, including PbS, CdSe/CdS, and InAs/CdSe/CdS core/shell nanoparticles. Applications that make use of the norbornene click-chemistry functionality will be presented, along with efforts to preserve the high quantum yield and colloidal stability in water. We also introduce a bidentate carboxylate-based ligand as part of an effort to enhance the quality of QDs through the chelate effect. This ligands enhances the PLQY at high temperature, as a result of surface-related trap state passivation. Finally, we describe the synthesis of a new functional group for generating derivatizable-QDs that can be easily copolymerized with the polyimidazole ligand (PIL), and that is reactive with tetrazine and, upon thermal activation, with thiols to form stable bioconjugates.

Download or read book Biological and Pharmaceutical Applications of Nanomaterials written by Polina Prokopovich and published by CRC Press. This book was released on 2015-06-26 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biological and Pharmaceutical Applications of Nanomaterials presents the findings of cutting-edge research activities in the field of nanomaterials, with a particular emphasis on biological and pharmaceutical applications. Divided into four sections-nanomaterials for drug delivery, antimicrobial nanomaterials, nanomaterials in biosensors, and safet