Download or read book Altering Quantum Confinement in Semiconductor Nanocrystals Using Strongly Interacting Exciton delocalizing Ligands written by Michael Steven Azzaro and published by . This book was released on 2019 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Semiconductor nanocrystals have long been studied as alternatives to traditional bulk semiconductor materials as active components in optoelectronic devices due to their size-tunable absorption and emission properties, as well as their ability to be processed into thin films from colloidal solutions. However, creating highly conductive nanocrystal solids remains a substantial challenge due to the presence of long (~2-3 nm), insulating “native ligands” that are used to terminate nanocrystal growth and provide colloidal stability following their synthesis. In this work we have used a variety of structural and spectroscopic characterization to investigate the chemical and physical changes associated with exchanging these native ligands for ligands that have the proper energetics and orbital symmetry conditions to interact strongly with nanocrystal electronic states, termed “exciton-delocalizing ligands”. This interaction is proposed to allow for delocalization of carriers beyond the nanocrystal core and into the ligand shell by reducing the potential energy barrier at the nanocrystal-ligand interface, which can be used to improve transport properties in nanocrystal solids. Colloidal nanocrystal samples were investigated to determine if this strong interaction impacts carrier cooling rates, as this would provide insight into the degree of mixed nanocrystal-ligand character of these states. Using transient absorption spectroscopy we measured the change in electron and hole cooling rates following ligand exchange with the exciton-delocalizing ligand phenyldithiocarbamate and found that when excited near the nanocrystal band edge, the valence band states of the nanocrystals interact more strongly with the ligand than those in the conduction band. Solid-state ligand exchange with phenyldithiocarbamate was then carried out on nanocrystal films to determine if the strong nanocrystal-ligand interaction of these exciton-delocalizing ligands impacts the exciton mobility in nanocrystal solids. Using a combination of transient absorption spectroscopy and kinetic Monte-Carlo simulations we have found that treatment with phenyldithiocarbamate yields a drastic increase in the diffusivity of excitons in nanocrystal films, and this improved transport occurs via a unique tunneling-type mechanism rather than more traditional Förster Resonance Energy Transfer. A combination of multidimensional spectroscopy and transient absorption were used to probe the electronic structure and dynamics of ligand-exchanged nanocrystals in both solution and films. Contributions to homogeneous broadening are assigned as primarily due to ligand fluctuations in solution and energy transfer between NCs in solids. Finally, by varying the initial excitation energy in the nanocrystal we find that more highly excited carriers exhibit a greater degree of delocalization resulting from a greater degree of mixed nanocrystal-ligand character of these states

Download or read book Quantum Confined Semiconductor Nanocrystals written by Wesley Chiang and published by American Chemical Society. This book was released on 2023-09-26 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today, the fascinating story of colloidal quantum dots has no series finale yet. Instead, there continue to be advancements in our understanding of the fundamental properties of these nanocrystals, each of these advancements catalyzing a spin-off into a new journey toward potential applications. These remarkable advancements include improving the synthesis techniques, characterizing nanocrystals at the single-particle level, and tailoring their properties for specific applications. The quantum-confined colloidal semiconductor nanocrystals field has witnessed a remarkable convergence of nanoscience, materials chemistry, and spectroscopy, resulting in unprecedented control over their properties. With ongoing research efforts, the potential of semiconductor nanocrystals continues to unfold. Scientists are exploring new materials, developing scalable synthesis methods, and pushing the boundaries of their applications in fields such as quantum computing, energy storage, and biological sensing. The authors take the reader into quantum confinement and quantum dots. While the contents of this primer are rather expansive, they merely scratch the surface of the complex voyage that quantum dot sciences have undergone. The authors have identified vital terminology, valuable concepts, techniques, and applications.

Download or read book Halide Perovskites written by Tze-Chien Sum and published by John Wiley & Sons. This book was released on 2019-03-25 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Real insight from leading experts in the field into the causes of the unique photovoltaic performance of perovskite solar cells, describing the fundamentals of perovskite materials and device architectures. The authors cover materials research and development, device fabrication and engineering methodologies, as well as current knowledge extending beyond perovskite photovoltaics, such as the novel spin physics and multiferroic properties of this family of materials. Aimed at a better and clearer understanding of the latest developments in the hybrid perovskite field, this is a must-have for material scientists, chemists, physicists and engineers entering or already working in this booming field.

Download or read book Colloidal Quantum Dot Optoelectronics and Photovoltaics written by Gerasimos Konstantatos and published by Cambridge University Press. This book was released on 2013-11-07 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: Captures the most up-to-date research in the field, written in an accessible style by the world's leading experts.

Download or read book Nanocrystal Quantum Dots Second Edition written by Victor I. Klimov and published by CRC Press. This book was released on 2010-04-21 with total page 485 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of recent advancements in colloidal nanocrystals and quantum-confined nanostructures, Nanocrystal Quantum Dots is the second edition of Semiconductor and Metal Nanocrystals: Synthesis and Electronic and Optical Properties, originally published in 2003. This new title reflects the book’s altered focus on semiconductor nanocrystals. Gathering contributions from leading researchers, this book contains new chapters on carrier multiplication (generation of multiexcitons by single photons), doping of semiconductor nanocrystals, and applications of nanocrystals in biology. Other updates include: New insights regarding the underlying mechanisms supporting colloidal nanocrystal growth A revised general overview of multiexciton phenomena, including spectral and dynamical signatures of multiexcitons in transient absorption and photoluminescence Analysis of nanocrystal-specific features of multiexciton recombination A review of the status of new field of carrier multiplication Expanded coverage of theory, covering the regime of high-charge densities New results on quantum dots of lead chalcogenides, with a focus studies of carrier multiplication and the latest results regarding Schottky junction solar cells Presents useful examples to illustrate applications of nanocrystals in biological labeling, imaging, and diagnostics The book also includes a review of recent progress made in biological applications of colloidal nanocrystals, as well as a comparative analysis of the advantages and limitations of techniques for preparing biocompatible quantum dots. The authors summarize the latest developments in the synthesis and understanding of magnetically doped semiconductor nanocrystals, and they present a detailed discussion of issues related to the synthesis, magneto-optics, and photoluminescence of doped colloidal nanocrystals as well. A valuable addition to the pantheon of literature in the field of nanoscience, this book presents pioneering research from experts whose work has led to the numerous advances of the past several years.

Download or read book Chemical Control of Charge Trapping and Charge Transfer Processes at the Organic Inorganic Interface Within Quantum Dot Organic Complexes written by and published by . This book was released on 2015 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Within the research program funded through the Early Career Research Award we designed complexes of colloidal semiconductor quantum dots (QDs) and organic molecules in which the interfacial chemistry controls the electronic structure and dynamics of the excitonic state of the QD. The program included two main projects; (1) investigation of the mechanisms by which organic surfactants control the quantum confinement of excitonic charge carriers; and (2) development of models for electron transfer between QDs and adsorbed molecules as a function of interfacial chemistry. This project was extremely successful in that our achievements in those two areas addressed the great majority of questions we outlined in the original proposal and answered questions I did not think to ask in that original proposal. Our work led to the discovery of "exciton delocalizing ligands", which change the electronic structure of colloidal semiconductor nanocrystals by altering, with small synthetic modifications to their surfaces, their most defining characteristic - the quantum confinement of their excited states. It also led to detailed, quantitative descriptions of how the surface chemistry of a QD dictates, thermodynamically and kinetically, the probability of exchange of electrons between the QD and a small molecule. We used two of the three major techniques in the proposal (transient photoluminescence and transient absorption). Electrogenerated chemiluminescence was also proposed, but was too technically difficult with these systems to be useful. Instead, NMR spectroscopy emerged as a major analytical tool in our studies. With the fundamental advancements we made with this project, we believe that we can design QDs to be the next great class of visible-light photocatalysts.

Download or read book Semiconductor Nanocrystals written by Alexander L. Efros and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 277 pages. Available in PDF, EPUB and Kindle. Book excerpt: A physics book that covers the optical properties of quantum-confined semiconductor nanostructures from both the theoretical and experimental points of view together with technological applications. Topics to be reviewed include quantum confinement effects in semiconductors, optical adsorption and emission properties of group IV, III-V, II-VI semiconductors, deep-etched and self assembled quantum dots, nanoclusters, and laser applications in optoelectronics.

Download or read book Quantum Confinement Beyond the Exciton Bhor Radius in Quantum Dot Nanoshells written by Dulanjan Padmajith Dharmasena Harankahage and published by . This book was released on 2020 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple exciton (MX) generation has been a significant part of the success of many semiconductor applications such as photoinduced energy conversion, stimulated emission and carrier multiplication. Generally, in small size semiconductor nanocrystals, MX processes are enhanced through quantum confinement of photoinduced charges. Unfortunately, the small particle volume of these semiconductor nanocrystals can also drive non-radiative Auger decay of multiple excitons reducing the MX feasibility in nanocrystal-based laser, photovoltaic and photoelectrochemical devices. Here, we reveal such Auger decay of biexcitons can be restrained with the utilization of quantum-well (QW) nanoshell heterostructures. The reported architecture reduces the Coulomb interactions between photoinduced charges which leads to enhanced biexciton lifetimes. Transient absorption measurements were used to demonstrate the increased biexciton lifetimes which revealed the cadmium based QW nanoshells (CdS/CdSe/CdS) increased the biexciton lifetime by more than 30 times compared to zero-dimensional CdSe nanocrystals. Suppression of Auger decay was attributed to the substantial confinement volume of the QW nanoshell architecture.

Download or read book Emerging Research in Science and Engineering Based on Advanced Experimental and Computational Strategies written by Felipe de Almeida La Porta and published by Springer Nature. This book was released on 2020-01-02 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, the authors discuss some of the main challenges and new opportunities in science and engineering research, which involve combining computational and experimental approaches as a promising strategy for arriving at new insights into composition–structure–property relations, even at the nanoscale. From a practical standpoint, the authors show that significant improvements in the material/biomolecular foresight by design, including a fundamental understanding of their physical and chemical properties, are vital and will undoubtedly help us to reach a new technological level in the future.

Download or read book Semiconductor Nanostructures written by Dieter Bimberg and published by Springer Science & Business Media. This book was released on 2008-06-03 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reducing the size of a coherently grown semiconductor cluster in all three directions of space to a value below the de Broglie wavelength of a charge carrier leads to complete quantization of the energy levels, density of states, etc. Such “quantum dots” are more similar to giant atoms in a dielectric cage than to classical solids or semiconductors showing a dispersion of energy as a function of wavevector. Their electronic and optical properties depend strongly on their size and shape, i.e. on their geometry. By designing the geometry by controlling the growth of QDs, absolutely novel possibilities for material design leading to novel devices are opened. This multiauthor book written by world-wide recognized leaders of their particular fields and edited by the recipient of the Max-Born Award and Medal 2006 Professor Dieter Bimberg reports on the state of the art of the growing of quantum dots, the theory of self-organised growth, the theory of electronic and excitonic states, optical properties and transport in a variety of materials. It covers the subject from the early work beginning of the 1990s up to 2006. The topics addressed in the book are the focus of research in all leading semiconductor and optoelectronic device laboratories of the world.

Download or read book Quantum Dot Molecules written by Jiang Wu and published by Springer Science & Business Media. This book was released on 2013-10-28 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: A quantum dot molecule (QDM) is composed of two or more closely spaced quantum dots or “artificial atoms.” In recent years, QDMs have received much attention as an emerging new artificial quantum system. The interesting and unique coupling and energy transfer processes between the “artificial atoms” could substantially extend the range of possible applications of quantum nanostructures. This book reviews recent advances in the exciting and rapidly growing field of QDMs via contributions from some of the most prominent researchers in this scientific community. The book explores many interesting topics such as the epitaxial growth of QDMs, spectroscopic characterization, and QDM transistors, and bridges between the fundamental physics of novel materials and device applications for future information technology. Both theoretical and experimental approaches are considered. Quantum Dot Molecules can be recommended for electrical engineering and materials science department courses on the science and design of advanced and future electronic and optoelectronic devices.

Download or read book Charge and Energy Transfer Dynamics in Molecular Systems written by Volkhard May and published by John Wiley & Sons. This book was released on 2011-04-27 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 3rd edition has been expanded and updated to account for recent developments, while new illustrative examples as well as an enlarged reference list have also been added. It naturally retains the successful concept of its predecessors in presenting a unified perspective on molecular charge and energy transfer processes, thus bridging the regimes of coherent and dissipative dynamics, and establishing a connection between classic rate theories and modern treatments of ultrafast phenomena. Among the new topics are: - Time-dependent density functional theory - Heterogeneous electron transfer, e.g. between molecules and metal or semiconductor surfaces - Current flows through a single molecule. While serving as an introduction for graduate students and researchers, this is equally must-have reading for theoreticians and experimentalists, as well as an aid to interpreting experimental data and accessing the original literature.

Download or read book Perovskite Quantum Dots written by Ye Zhou and published by Springer Nature. This book was released on 2020-08-27 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses perovskite quantum dots, discussing their unique properties, synthesis, and applications in nanoscale optoelectronic and photonic devices, as well as the challenges and possible solutions in the context of device design and the prospects for commercial applications. It particularly focuses on the luminescent properties, which differ from those of the corresponding quantum dots materials, such as multicolor emission, fluorescence narrowing, and tunable and switchable emissions from doped nanostructures. The book first describes the characterization and fabrication of perovskite quantum dots. It also provides detailed methods for analyzing the electrical and optical properties, and demonstrates promising applications of perovskite quantum dots. Furthermore, it presents a series of optoelectronic and photonic devices based on functional perovskite quantum dots, and explains the incorporation of perovskite quantum dots in semiconductor devices and their effect of the performance. It also explores the challenges related to optoelectronic devices, as well as possible strategies to promote their commercialization. As such, this book is a valuable resource for graduate students and researchers in the field of solid-state materials and electronics wanting to gain a better understanding of the characteristics of quantum dots, and the fundamental optoelectronic properties and operation mechanisms of the latest perovskite quantum dot-based devices.

Download or read book Semiconductor Nanocrystal Quantum Dots written by Andrey Rogach and published by Springer Science & Business Media. This book was released on 2008-09-02 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book to specifically focus on semiconductor nanocrystals, and address their synthesis and assembly, optical properties and spectroscopy, and potential areas of nanocrystal-based devices. The enormous potential of nanoscience to impact on industrial output is now clear. Over the next two decades, much of the science will transfer into new products and processes. One emerging area where this challenge will be very successfully met is the field of semiconductor nanocrystals. Also known as colloidal quantum dots, their unique properties have attracted much attention in the last twenty years.

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 Photosynergetic Responses in Molecules and Molecular Aggregates written by Hiroshi Miyasaka and published by Springer Nature. This book was released on 2020-09-05 with total page 593 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book compiles the accomplishments of the recent research project on photochemistry “Photosynergetics”, supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan, aiming to develop and elucidate new methods and molecules leading to advanced utilization of photo-energies. Topics include photochemical responses induced by multiple excitation, multiphoton absorption, strong modulation of electronic states, developments of new photofunctional molecules, mesoscopic actuations induced by photoexcitation, and novel photoresponses in molecules and molecular assemblies. The authors stress that these approaches based on the synergetic interaction among many photons and many molecules enable the expansion of the accessibility to specific electronic states. As well, they explain how the development of reaction sequences and molecules/molecular assemblies ensure “additivity” and “integration” without loss of the photon energy, leading to new photoresponsive assemblies in meso- and macroscopic scales.

Download or read book Nanomaterials Chemistry written by C. N. R. Rao and published by John Wiley & Sons. This book was released on 2007-09-24 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: With this handbook, the distinguished team of editors has combined the expertise of leading nanomaterials scientists to provide the latest overview of this field. They cover the whole spectrum of nanomaterials, ranging from theory, synthesis, properties, characterization to application, including such new developments as quantum dots, nanoparticles, nanoporous materials, nanowires, nanotubes, and nanostructured polymers. The result is recommended reading for everybody working in nanoscience: Newcomers to the field can acquaint themselves with this exciting subject, while specialists will find answers to all their questions as well as helpful suggestions for further research.