Download or read book Vibrational Properties and Exciton phonon Interactions in Lead Sulfide Nanocrystals written by Todd Douglas Krauss and published by . This book was released on 1998 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Excitonic Properties and Hot carrier Cooling in Lead Sulfide Quantum Dots written by Eric Ronald Kennehan and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Hot-carrier cooling, which has been predicted to be slowed in semiconductor quantum dots (QDs) due to the anticipated hot-phonon bottleneck, has not been readily observed, with carrier cooling rates of QDs approaching bulk cooling rates. PbS QDs are excellent potential candidates to exhibit extended hot-carrier lifetimes since confinement of both electrons and holes are nearly identical, thus circumventing an efficient Auger mechanism which has been found to increase cooling rates in other materials. Despite, the advantages of PbS QDs for enhanced hot-carrier lifetimes, rapid thermalization of hot-carriers persist in these materials and the mechanism which directs this fast cooling is not well understood. Using a combination of steady-state and time-resolve, electronic optical spectroscopy, this work has provided new insights into the behavior of excited electronic states in PbS QDs. This work identified the spectroscopic signature of the formally forbidden 1Se(h)-1De(h) intraband transition, allowing vibronic coupling to be investigated for this high energy state, along with the 1Pe(h) and band edge states. It was determined that significant homogenous broadening of these states occurs as a result of a highly size-dependent exciton-phonon coupling mechanism. It is this vibronic coupling that results in resonant energy relaxation pathways between the intraband states of the QDs that are amplified for smaller diameter nanocrystals, leading to rapid bulk-like cooling in these materials. Additionally, steady-state and time-resolved vibrational spectroscopy were used to identify possible sources of the vibronic coupling in PbS QDs. Through this work, vibrational coupling in PbS QDs, was found to be independent of the types of ligands at the crystalline surface and was in fact mediated by the surface phonons. Strong nonadiabatic coupling is occurs at the QD surface because of the broad phonon spectrum associated with the strained crystalline lattice, dangling bonds, and exposed crystal facets. This work suggests that surface modification techniques that reduce the coupling of electronic states to surface phonons may enable quantum confined structures with slower carrier cooling rates. Such surface modifications may include the use of thin inorganic shells or controlled composition gradients to reduce dangling bonds and tune the lattice strain at QD surfaces.

Download or read book Excitonic and Vibrational Dynamics in Nanotechnology written by Svetlana Kilina and published by CRC Press. This book was released on 2019-10-10 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book investigates QDs and SWCNTs using quantum-chemical calculations that describe intricate details of excited-state phenomena and provides information about the mechanisms that occur on the atomic level and that are extremely difficult, if not impossible, to probe experimentally. It delivers, consistently and coherently, a novel approach to nanomaterials which is promising for today's technologies as well as their future. This approach elegantly overcomes computational difficulties known in the field and shares ways to reach top performance in the description of combined quantum effects of molecular vibrations and exciton formation on realistic-size numerical models. The reader will acquire an understanding of the pioneering methodolo

Download or read book Focus on Condensed Matter Physics Research written by John V. Chang and published by Nova Publishers. This book was released on 2005 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: Condensed matter is one of the most active fields of physics, with a stream of discoveries in areas from superfluidity and magnetism to the optical, electronic and mechanical properties of materials such as semiconductors, polymers and carbon nanotubes. It includes the study of well-characterised solid surfaces, interfaces and nanostructures as well as studies of molecular liquids (molten salts, ionic solutions, liquid metals and semiconductors) and soft matter systems (colloidal suspensions, polymers, surfactants, foams, liquid crystals, membranes, biomolecules etc., including glasses and biological aspects of soft matter. This book presents state-of-the-art research in this exciting field.

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 Exciton Dynamics in Lead Halide Perovskite Nanocrystals written by Bernhard Johann Bohn and published by Springer Nature. This book was released on 2021-05-18 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: Less than a decade ago, lead halide perovskite semiconductors caused a sensation: Solar cells exhibiting astonishingly high levels of efficiency. Recently, it became possible to synthesize nanocrystals of this material as well. Interestingly; simply by controlling the size and shape of these crystals, new aspects of this material literally came to light. These nanocrystals have proven to be interesting candidates for light emission. In this thesis, the recombination, dephasing and diffusion of excitons in perovskite nanocrystals is investigated using time-resolved spectroscopy. All these dynamic processes have a direct impact on the light-emitting device performance from a technology point of view. However, most importantly, the insights gained from the measurements allowed the author to modify the nanocrystals such that they emitted with an unprecedented quantum yield in the blue spectral range, resulting in the successful implementation of this material as the active layer in an LED. This represents a technological breakthrough, because efficient perovskite light emitters in this wavelength range did not exist before.

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 Materials for Sustainable Energy written by Vincent Dusastre and published by World Scientific. This book was released on 2011 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: The search for cleaner, cheaper, smaller and more efficient energy technologies has to a large extent been motivated by the development of new materials. The aim of this collection of articles is therefore to focus on what materials-based solutions can offer and show how the rationale design and improvement of their physical and chemical properties can lead to energy-production alternatives that have the potential to compete with existing technologies. In terms of alternative means to generate electricity that utilize renewable energy sources, the most dramatic breakthroughs for both mobile (i.e., transportation) and stationary applications are taking place in the fields of solar and fuel cells. And from an energy-storage perspective, exciting developments can be seen emerging from the fields of rechargeable batteries and hydrogen storage.

Download or read book Physics Briefs written by and published by . This book was released on 1993 with total page 1420 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Semiconductors written by and published by . This book was released on 1998 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Semiconductor Quantum Dots written by Y. Masumoto and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor quantum dots represent one of the fields of solid state physics that have experienced the greatest progress in the last decade. Recent years have witnessed the discovery of many striking new aspects of the optical response and electronic transport phenomena. This book surveys this progress in the physics, optical spectroscopy and application-oriented research of semiconductor quantum dots. It focuses especially on excitons, multi-excitons, their dynamical relaxation behaviour and their interactions with the surroundings of a semiconductor quantum dot. Recent developments in fabrication techniques are reviewed and potential applications discussed. This book will serve not only as an introductory textbook for graduate students but also as a concise guide for active researchers.

Download or read book Cadmium Telluride Quantum Dots written by John Donegan and published by CRC Press. This book was released on 2016-04-19 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last two decades, semiconductor quantum dots-small colloidal nanoparticles-have garnered a great deal of scientific interest because of their unique properties. Among nanomaterials, CdTe holds special technological importance as the only known II-VI material that can form conventional p-n junctions. This makes CdTe very important for the dev

Download or read book Quantum Dot Heterostructures written by Dieter Bimberg and published by John Wiley & Sons. This book was released on 1999-03-17 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: Da die Nachfrage nach immer schnelleren und kleineren Halbleiterbauelementen stetig wächst, sind Quanten-Dots und -Pyramiden rasant in den Mittelpunkt der Halbleiterforschung gerückt. Dieses Buch vermittelt einen umfassenden Überblick über den aktuellen Forschungsstand auf diesem Gebiet. Behandelt werden u.a. Fragen, wie Strukturen aufgebaut, wie sie charakterisiert werden und wie sie die Leistungsfähigkeit der Bauelemente bestimmen. (11/98)

Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2540 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nanostructured Lead Cadmium and Silver Sulfides written by Stanislav I. Sadovnikov and published by Springer. This book was released on 2017-09-02 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents and analyzes the influence of small size particles of lead, cadmium and silver sulfide on the properties of nonstoichiometric semiconductors. Important nonstoichiometry aspects in nanostructures are discussed, such as the distribution of sulfur atoms in nanofilms, a non-periodic distribution of the atomic planes in nanoparticles, interdependent changes in crystal structure of nanocrystalline material. Tuning the stoichiometry allows to obtain superionic conductivity and catalytic activity under visible light. The wavelength of the luminescence of nanoparticles changes with the size of the nanoparticles. Various methods to prepare nanostructured sulfides are described. Special attention is given to the hydrochemical bath deposition as a universal method for the synthesis of sulfides as nanofilms, stable colloidal solutions, quantum dots, isolated nanoparticles with a protective shell and heteronanostructures. The effect of nanoparticle size and nonstoichiometry on the band gap, optical and thermal properties of nanostructured sulfides is also considered. The novel applications of sulfide nanoparticles in nanoelectronics, catalysis, nanobiology and nanomedicine are sketched.

Download or read book Handbook of Self Assembled Semiconductor Nanostructures for Novel Devices in Photonics and Electronics written by Mohamed Henini and published by Elsevier Science. This book was released on 2008 with total page 841 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1969, Leo Esaki (1973 Nobel Laureate) and Ray Tsu from IBM, USA, proposed research on “man-made crystals” using a semiconductor superlattice (a semiconductor structure comprising several alternating ultra-thin layers of semiconductor materials with different properties). This invention was perhaps the first proposal to advocate the engineering of a new semiconductor material, and triggered a wide spectrum of experimental and theoretical investigations. However, the study of what are now called low dimensional structures (LDS) began in the late 1970's when sufficiently thin epitaxial layers were first produced following developments in the technology of epitaxial growth of semiconductors, mainly pioneered in industrial laboratories for device purposes. The LDS are materials structures whose dimensions are comparable with inter-atomic distances in solids (i.e. nanometre, nm). Their electronic properties are significantly different from the same material in bulk form. These properties are changed by quantum effects. At the inception of their investigation it was already clear that such structures were of great scientific interest and excitement and their novel properties caused by quantum effects offered potential for application in new devices. Moreover these complex LDS offer device engineers new design opportunities for tailor-made new generation electronic devices. The LDS could be considered as a new branch of condensed matter physics because of the large variety of possible structures and the changes in the physical processes. One of the promising fabrication methods to produce and study structures with a dimension less than two such as quantum wires and quantum dots, in order to realise novel devices that make use of low-dimensional confinement effects, is self-organisation. Self-assembled nanostructured materials offer a number of advantages over conventional material technologies in a wide-range of sectors. Clearly, future research work on self-assembled nanostructures will connect diverse areas of material science, physics, chemistry, electronics and optoelectronics. Key Features: - Contributors are world leaders in the field - Brings together all the factors which are essential in self-organisation of quantum nanostructures - Reviews the current status of research and development in self-organised nanostructured materials - Provides a ready source of information on a wide range of topics - Useful to any scientist who is involved in nanotechnology - Excellent starting point for workers entering the field - Serves as an excellent reference manual