Understanding the Reactivity of Molecular Precursors to Colloidal Nanocrystals PDF Download
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Languages : en
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Author: Jeffrey A. Gerbec
Publisher:
ISBN: 9780542571671
Category :
Languages : en
Pages : 356
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Colloidal semiconductor nanocrystals, with unique size-dependent optical properties, have great promise for integration into next generation technologies including solid-state lighting and biological labeling. A general method of reproducible, large scale and environmentally safe synthetic preparation becomes crucial for integration in commercial devices. In addition to the synthetic protocol, an understanding of the surfaces of the as prepared material is critical for obtaining a high quantum yield that is stable for long periods of time in ambient conditions. In this dissertation, a new synthetic approach to general colloidal nanocrystals is presented. Microwave heating of molecular precursors increases the rate of reaction from days to minutes for a host of nanomaterials. The most relevant for the study of inorganic phosphors is CdSe and InP and their respective ternary analogs. Post synthetic surface treatment of the as prepared material show a tremendous increase in the QY for as prepared InP and InGaP. Post synthetic surface treatment is carried out by photoactivated etching with dilute HF. In the case of InGaP, the QY reaches 0.80 from 0.05 in a matter of minutes. Other surface treatment strategies that address the stability is carried out by forming epitaxial core shell structures. It is shown that using ZnS as a wide band gap shelling material, the QY of InP reaches 0.42 in solution and is stable for months. These are significant steps toward the engineering of semiconductor quantum dot phosphors for solid state lighting and biological labeling.
Author: Beata Luszczynska
Publisher: John Wiley & Sons
ISBN: 3527814957
Category : Technology & Engineering
Languages : en
Pages : 688
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Provides first-hand insights into advanced fabrication techniques for solution processable organic electronics materials and devices The field of printable organic electronics has emerged as a technology which plays a major role in materials science research and development. Printable organic electronics soon compete with, and for specific applications can even outpace, conventional semiconductor devices in terms of performance, cost, and versatility. Printing techniques allow for large-scale fabrication of organic electronic components and functional devices for use as wearable electronics, health-care sensors, Internet of Things, monitoring of environment pollution and many others, yet-to-be-conceived applications. The first part of Solution-Processable Components for Organic Electronic Devices covers the synthesis of: soluble conjugated polymers; solution-processable nanoparticles of inorganic semiconductors; high-k nanoparticles by means of controlled radical polymerization; advanced blending techniques yielding novel materials with extraordinary properties. The book also discusses photogeneration of charge carriers in nanostructured bulk heterojunctions and charge carrier transport in multicomponent materials such as composites and nanocomposites as well as photovoltaic devices modelling. The second part of the book is devoted to organic electronic devices, such as field effect transistors, light emitting diodes, photovoltaics, photodiodes and electronic memory devices which can be produced by solution-based methods, including printing and roll-to-roll manufacturing. The book provides in-depth knowledge for experienced researchers and for those entering the field. It comprises 12 chapters focused on: ? novel organic electronics components synthesis and solution-based processing techniques ? advanced analysis of mechanisms governing charge carrier generation and transport in organic semiconductors and devices ? fabrication techniques and characterization methods of organic electronic devices Providing coverage of the state of the art of organic electronics, Solution-Processable Components for Organic Electronic Devices is an excellent book for materials scientists, applied physicists, engineering scientists, and those working in the electronics industry.
Author: Allen W. Apblett
Publisher: Elsevier
ISBN: 0128203447
Category : Technology & Engineering
Languages : en
Pages : 630
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Book Description
Nanomaterials via Single-Source Precursors: Synthesis, Processing and Applications presents recent results and overviews of synthesis, processing, characterization and applications of advanced materials for energy, electronics, biomedicine, sensors and aerospace. A variety of processing methods (vapor, liquid and solid-state) are covered, along with materials, including metals, oxides, semiconductor, sulfides, selenides, nitrides, and carbon-based materials. Production of quantum dots, nanoparticles, thin films and composites are described by a collection of international experts. Given the ability to customize the phase, morphology, and properties of target materials, this “rational approach to synthesis and processing is a disruptive technology for electronic, energy, structural and biomedical (nano)materials and devices. The use of single-source chemical precursors for materials processing technology allows for intimate elemental mixing and hence production of complex materials at temperatures well below traditional physical methods and those involving direct combination of elements. The use of lower temperatures enables thin-film deposition on lightweight polymer substrates and reduces damage to complex devices structures such as used in power, electronics and sensors. Discusses new approaches to synthesis or single-source precursors (SSPs) and the concept of rational design of materials Includes materials processing of SSPs in the design of new materials and novel devices Provides comprehensive coverage of the subject (materials science and chemistry) as related to SSPs and the range of potential applications
Author: Kallum M. Koczkur
Publisher: American Chemical Society
ISBN: 0841299013
Category : Science
Languages : en
Pages : 164
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Book Description
Our society depends heavily on metals. They are ubiquitous construction materials, critical interconnects in integrated circuits, common coinage materials, and more. Excitingly, new uses for metals are emerging with the advent of nanoscience, as metal crystals with nanoscale dimensions can display new and tunable properties. The optical and photothermal properties of metal nanocrystals have led to cancer diagnosis and treatment platforms now in clinical trials, while, at the same time, the ability to tune the surface features of metal nanocrystals is giving rise to designer catalysts that enable more sustainable use of precious resources. These are just two examples of how metal nanocrystals are addressing important social needs.
Author: Swamy Pittala
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Spin-based electronics use the spins of electrons in addition to their charges and have potential applications to create a next generation of quantum computers, capable of storing vast amounts of data in an energy-efficient way. Diluted magnetic semiconductor quantum dots (DMS-QDs) have shown great promise as ideal materials for application in spin-based electronics. However, doping impurities into quantum confined colloidal nanocrystals (NCs) has been a great challenge due to the lack of control over the dopant reactivity during the specific stages of nucleation and growth. The mechanism of dopant incorporation into nanocrystals is complex and well-defined and atomically precise molecular clusters can provide detailed knowledge and novel insights into the doping process. This work focuses on the synthesis of Co2+ substituted CdS and ZnS based molecular clusters and understanding doping mechanism at the molecular level and use these clusters as precursors to make doped nanocrystals. The cation exchange rates and thermodynamic stability of dopants in the smallest tetrameric clusters is found to depend mainly on the identity of the host cation in the cluster. The surface ligand dynamics of clusters directly control the rate of dopant ion exchange into molecular clusters. As the size of molecular clusters increases the ligand dynamics decreases and dopant exchange into these larger clusters becomes less feasible. We developed a method to synthesize doped NCs using these pre-doped magnetic molecular chalcogenide clusters, as single-source precursors. We obtained very high concentration of cobalt impurities into CdS nanocrystals without undergoing spinodal decomposition. This high doping level is attributed to the growth mechanism that involves formation of dopant substituted metastable magic-sized nuclei (CdS)34 before the critical nuclei during the synthesis. Furthermore, the particular growth mechanism of doped nanocrystals can be controlled by the size of diluted magnetic molecular precursors. The synthetic strategy demonstrated here utilizes magnetic inorganic clusters as true single-source precursors and provides an effective and tunable route to synthesize doped nanocrystals with high dopant concentrations.
Author: Ana Luísa Daniel-da-Silva
Publisher: Royal Society of Chemistry
ISBN: 1788019814
Category : Science
Languages : en
Pages : 221
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Book Description
The chemistry of nanomaterials has developed considerably in the past two decades, and concepts that have emerged from these developments are now well established. The surface modification of nanoparticles is a subject of intense research interest given its importance for many applications across a number of disciplines. This comprehensive guide is the first to be devoted to the surface chemistry of inorganic nanocrystals. Following an introduction to the physical chemistry of surfaces, chapters cover topics such as the surface modification of nanoparticles, water compatible, polymer-based, and inorganic nanocomposites, as well as relevant applications in catalysis, biotechnology and nanomedicine. Highlighting recent advances, Surface Chemistry of Colloidal Nanocrystals provides an integrated approach to chemical aspects related to the surface of nanocrystals. Written by prestigious scientists, this will be a useful resource for students and researchers working in surface science, nanoscience and materials science as well as those interested in the applications of the nanomaterials in areas such as health science, biology, and environmental engineering.
Author: Simona E. Hunyadi Murph
Publisher: Springer
ISBN: 3319596624
Category : Science
Languages : en
Pages : 471
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Book Description
This book reviews recent advances in the synthesis, characterization, and physico-chemical properties of anisotropic nanomaterials. It highlights various emerging applications of nanomaterials, including sensing and imaging, (bio)medical applications, environmental protection, plasmonics, catalysis, and energy. It provides an excellent and comprehensive overview of the effect that morphology and nanometric dimension has on the physico-chemical properties of various materials and how this leads to novel applications.
Author: Marissa Anne Caldwell
Publisher: Stanford University
ISBN:
Category :
Languages : en
Pages : 113
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Book Description
Phase change (PC) memory has emerged as a leading candidate for next generation information storage technology. Based on the reversible amorphous-crystalline phase transition of chalcogenide materials, PC technology has already been commercialized through the optical disk industry and is currently being evaluated for non-volatile electronic data storage as phase change random access memory (PCRAM). In either the optical or electronic application, device performance relies on the material properties of the active phase change material (PCM). Traditionally deposited through physio-chemical routes such as sputtering or chemical vapor deposition, the PCM fundamentally limits PC scaling potential as it is expected that key properties will change as the volume of PCM decreases. Colloidal nanoparticle systems provide a unique opportunity to systematically study the properties of materials in the nanosize regime due to the potential for exquisite composition and size control. In this talk, I will present the first colloidal nanoparticle system of a known phase change material. Colloidal GeTe nanoparticles 1.4-4nm in diameter were synthesized through a co-precipitation route and characterized by transmission electron microscopy, energy dispersive x-ray spectroscopy and x-ray diffraction. Nuclear magnetic resonance spectroscopy (1H and 31P) was used to elucidate the molecular species involved in the reaction pathway and found that a metal center mediated proton transfer is necessary to mediate the relative reactivity of the reactants. In addition, a post-synthetic size selective procedure was developed to separate the nanoparticles into distinct size ranges. Using in-situ heating, the size dependent crystallization temperature was measured by XRD and was found to increase with decreasing nanoparticle diameter suggesting favorable improvements in lifetime data retention for scaled PCRAM cells. To evaluate the potential use in PCRAM devices, electrical measurements were also collected on nanoparticle films. Resistance versus temperature measurements revealed that nanoparticle films retained the high resistive contrast between the amorphous and crystalline phases necessary for PCRAM operation. After design optimization, PCRAM cells were fabricated utilizing the nanoparticles as a solution processable precursor to the PCM. Completed cells showed reversible switching, including threshold switching, characteristic of PCRAM operation. Cycling up to 200 times, the cells are the best performing solution processed PCRAM devices reported to date, suggesting that colloidal nanoparticles are a viable route to PCMs.
Author: Mario Caironi
Publisher: John Wiley & Sons
ISBN: 3527679995
Category : Technology & Engineering
Languages : en
Pages : 588
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Book Description
From materials to applications, this ready reference covers the entire value chain from fundamentals via processing right up to devices, presenting different approaches to large-area electronics, thus enabling readers to compare materials, properties and performance. Divided into two parts, the first focuses on the materials used for the electronic functionality, covering organic and inorganic semiconductors, including vacuum and solution-processed metal-oxide semiconductors, nanomembranes and nanocrystals, as well as conductors and insulators. The second part reviews the devices and applications of large-area electronics, including flexible and ultra-high-resolution displays, light-emitting transistors, organic and inorganic photovoltaics, large-area imagers and sensors, non-volatile memories and radio-frequency identification tags. With its academic and industrial viewpoints, this volume provides in-depth knowledge for experienced researchers while also serving as a first-stop resource for those entering the field.
