Download or read book Modelling Charge and Exciton Transport in Polymeric and Molecular Systems written by Rocco P. Fornari and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Charge and Exciton Transport through Molecular Wires written by Laurens D. A. Siebbeles and published by John Wiley & Sons. This book was released on 2011-07-18 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: As functional elements in opto-electronic devices approach the singlemolecule limit, conducting organic molecular wires are the appropriate interconnects that enable transport of charges and charge-like particles such as excitons within the device. Reproducible syntheses and a thorough understanding of the underlying principles are therefore indispensable for applications like even smaller transistors, molecular machines and light-harvesting materials. Bringing together experiment and theory to enable applications in real-life devices, this handbook and ready reference provides essential information on how to control and direct charge transport. Readers can therefore obtain a balanced view of charge and exciton transport, covering characterization techniques such as spectroscopy and current measurements together with quantitative models. Researchers are thus able to improve the performance of newly developed devices, while an additional overview of synthesis methods highlights ways of producing different organic wires. Written with the following market in mind: chemists, molecular physicists, materials scientists and electrical engineers.
Download or read book Handbook of Materials Modeling written by Sidney Yip and published by Springer Science & Business Media. This book was released on 2007-11-17 with total page 2903 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first reference of its kind in the rapidly emerging field of computational approachs to materials research, this is a compendium of perspective-providing and topical articles written to inform students and non-specialists of the current status and capabilities of modelling and simulation. From the standpoint of methodology, the development follows a multiscale approach with emphasis on electronic-structure, atomistic, and mesoscale methods, as well as mathematical analysis and rate processes. Basic models are treated across traditional disciplines, not only in the discussion of methods but also in chapters on crystal defects, microstructure, fluids, polymers and soft matter. Written by authors who are actively participating in the current development, this collection of 150 articles has the breadth and depth to be a major contributor toward defining the field of computational materials. In addition, there are 40 commentaries by highly respected researchers, presenting various views that should interest the future generations of the community. Subject Editors: Martin Bazant, MIT; Bruce Boghosian, Tufts University; Richard Catlow, Royal Institution; Long-Qing Chen, Pennsylvania State University; William Curtin, Brown University; Tomas Diaz de la Rubia, Lawrence Livermore National Laboratory; Nicolas Hadjiconstantinou, MIT; Mark F. Horstemeyer, Mississippi State University; Efthimios Kaxiras, Harvard University; L. Mahadevan, Harvard University; Dimitrios Maroudas, University of Massachusetts; Nicola Marzari, MIT; Horia Metiu, University of California Santa Barbara; Gregory C. Rutledge, MIT; David J. Srolovitz, Princeton University; Bernhardt L. Trout, MIT; Dieter Wolf, Argonne National Laboratory.
Download or read book Theoretical and Spectroscopic Studies of Energy and Charge Transport in Organic Semiconductors written by Patrick Charles Tapping and published by . This book was released on 2017 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of organic semiconductor devices is heavily dependent on the precise molecular-level arrangement and overall morphology of the functional layers. In organic photovoltaic applications, exciton mobility, fission/fusion or dissociation, as well as charge transport and separation are some of the morphology-dependent processes that are of interest for efficient device design. In this work a combination of experimental and computational techniques are used to elucidate the behaviour of excitons in conjugated polymer and small-molecule semiconductor systems. While there is an emphasis on photovoltaic applications, many concepts are generally applicable to other organic electronic applications such organic light emitting diodes and photodetectors. In Chapter 3, a pump-push-probe transient absorption technique is used to observe high-energy "hot" excitons formed by photoexcitation of the conjugated polymer poly(3-hexylthiophene) (P3HT). The work demonstrates the ability to clearly isolate the transient signal of the hot exciton decay processes from the thermalised exciton population, where picosecond and sub-picosecond relaxation of hot excitons through torsional motion in the disordered polymer chain is observed. In addition, the push-induced dissociation of high-energy excitons into free charge carriers is able to be quantified and an upper bound on the exciton binding energy determined. Spectroscopic experiments on P3HT are accompanied by a hybrid quantum-classical exciton hopping model in Chapter 4. Coarse-grained molecular dynamics are used to obtain realistic structures of P3HT free chains and nanofibre aggregates, to which a Frenkel-Holstein exciton model and Monte Carlo hopping simulation is applied. This novel approach captures exciton transport properties of polymer systems with a monomer-level of detail unachievable with continuum or lattice style models, but at a large scale infeasible with fully quantum calculations. Reasonable quantitative agreement with experimental observables is obtained, offering insight into the morphology-dependence of exciton transport in conjugated polymers. In particular, the observed tendency for exciton migration to the core of the polymer aggregate can explain the relatively poor performance of highly crystalline or nanofibre-based polymer solar cells, as well as the unusually high fluorescence yield of aqueous P3HT nanoparticles. The effect of disorder in small molecule semiconductor films is investigated in Chapter 5 in the context of singlet exciton fission and triplet fusion under the influence of applied magnetic fields. A model is presented that extends the historical theory of molecular spin interactions in crystalline materials and corrects the current understanding in the literature regarding such disordered solid-phase systems. The possibility of using the fluorescence response to magnetic fields to probe the morphology and degree disorder in the films is demonstrated. Extending the model to solution-phase behaviour is then discussed in Chapter 6, where the potential of improving the light-harvesting ability of solar cells through a molecular triplet-triplet annihilation upconversion process is considered. Molecular dynamics simulations are used to obtain physical parameters and collision geometry of the emitter molecules in solution. The complications of applying a static model of triplet fusion to the dynamic solution-phase behaviour are elucidated and the potential of synthesising an ideal upconversion emitter molecule is discussed.
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 Electronic and Optical Properties of Conjugated Polymers written by William Barford and published by OUP Oxford. This book was released on 2013-04-04 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conjugated polymers have important technological applications, including solar cells and light emitting devices. They are also active components in many important biological processes. In recent years there have been significant advances in our understanding of these systems, owing to both improved experimental measurements and the development of advanced computational techniques. The aim of this book is to describe and explain the electronic and optical properties of conjugated polymers. It focuses on the three key roles of electron-electron interactions, electron-nuclear coupling, and disorder in determining the character of the electronic states, and it relates these properties to experimental observations in real systems. A number of important optical and electronic processes in conjugated polymers are also described. The second edition has a more extended discussion of excitons in conjugated polymers. There is also a new chapter on the static and dynamical localization of excitons.
Download or read book Modelling Charge Transport for Organic Solar Cells within Marcus Theory written by Riccardo Volpi and published by Linköping University Electronic Press. This book was released on 2016-12-20 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the technological advancement of modern society, electronic devices are getting progressively more integrated in our everyday lives. Their continuouslygrowing presence is generating numerous concerns about costs, efficiency and the environmental impact of the electronic waste. In this context, organic electronics is finding its way through the market, allowing for potentially low-cost, light, flexible, transparent and environmentally friendly electronics. Despite the numerous successes of organic electronics, the functioning of several categories of organic devices still represents a technological challenge, due to problems like low efficiencies and stabilities (degradation over time). Organic devices are composed by one or more organic materials depending on the particular application. The conformation and electronic structure of the organic molecules as well as their supramolecular arrangement in the single phase or at the interface are known to strongly a affect the mobility and/or the efficiency of the device. While there is consensus on the fundamental physics of organic devices, we still lack a detailed comprehensive theory able to fully explain experimental data. In this thesis we focus on trying to expand our knowledge of charge transport in organic materials through theoretical modelling and simulation of organic electronic devices. While the methodology developed is generally valid for any organic device, we will particularly focus on the case represented by organic photovoltaics. The morphology of the system is obtained by molecular dynamics simulations. Marcus theory is used to calculate the hopping rate of the charge carriers and subsequently study the possibility of free charge carriers production in an organic solar cell. The theory is then compared both with Kinetic Monte Carlo simulations and with experiments to identify the main pitfalls of the actual theory and ways to improve it. The Marcus rate between two molecules depends on the molecular orbital energies, the transfer integral between the two molecules and the reorganization energy. The orbital energies and the transfer integrals between two neighbouring molecules are obtained through quantum mechanical calculations in vacuum. Electrostatic effects of the environment are included through atomic charges and atomic polarizabilities, producing a correction both to the orbital energy and to the reorganization energy. We have studied several systems in the single phase (polyphenylene vinylene, C60, PC61BM) and at the interface between two organic materials (anthracene/C60, TQ1/PC71BM). We show how a combination of different methodologies can be used to obtain a realistic ab-initio model of organic devices taking into account environmental effects. This allows us to obtain qualitative agreement with experimental data of mobility in the single phase and to determine whether or not two materials are suitable to be used together in an organic solar cell.
Download or read book Semiconducting Polymer Composites written by Xiaoniu Yang and published by John Wiley & Sons. This book was released on 2012-10-05 with total page 553 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first part of Semiconducting Polymer Composites describes the principles and concepts of semiconducting polymer composites in general, addressing electrical conductivity, energy alignment at interfaces, morphology, energy transfer, percolation theory and processing techniques. In later chapters, different types of polymer composites are discussed: mixtures of semiconducting and insulating or semiconducting and semiconducting components, respectively. These composites are suitable for a variety of applications that are presented in detail, including transistors and solar cells, sensors and detectors, diodes and lasers as well as anti-corrosive and anti-static surface coatings.
Download or read book The Theory of Open Quantum Systems written by Heinz-Peter Breuer and published by Oxford University Press, USA. This book was released on 2002 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book treats the central physical concepts and mathematical techniques used to investigate the dynamics of open quantum systems. To provide a self-contained presentation the text begins with a survey of classical probability theory and with an introduction into the foundations of quantum mechanics with particular emphasis on its statistical interpretation. The fundamentals of density matrix theory, quantum Markov processes and dynamical semigroups are developed. The most important master equations used in quantum optics and in the theory of quantum Brownian motion are applied to the study of many examples. Special attention is paid to the theory of environment induced decoherence, its role in the dynamical description of the measurement process and to the experimental observation of decohering Schrodinger cat states. The book includes the modern formulation of open quantum systems in terms of stochastic processes in Hilbert space. Stochastic wave function methods and Monte Carlo algorithms are designed and applied to important examples from quantum optics and atomic physics, such as Levy statistics in the laser cooling of atoms, and the damped Jaynes-Cummings model. The basic features of the non-Markovian quantum behaviour of open systems are examined on the basis of projection operator techniques. In addition, the book expounds the relativistic theory of quantum measurements and discusses several examples from a unified perspective, e.g. non-local measurements and quantum teleportation. Influence functional and super-operator techniques are employed to study the density matrix theory in quantum electrodynamics and applications to the destruction of quantum coherence are presented. The text addresses graduate students and lecturers in physics and applied mathematics, as well as researchers with interests in fundamental questions in quantum mechanics and its applications. Many analytical methods and computer simulation techniques are developed and illustrated with the help of numerous specific examples. Only a basic understanding of quantum mechanics and of elementary concepts of probability theory is assumed.
Download or read book Energy Materials Discovery written by Geoffrey A Ozin and published by Royal Society of Chemistry. This book was released on 2022-06-13 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: Materials have the potential to be the centrepiece for the transition to viable renewable energy technologies if they realise a specific suite of properties and achieve a desired set of performance metrics. The envisioned transition involves the discovery of materials that enable generation, conversion, storage, transmission, and utilization of renewable energy. This book presents, through the eye of materials chemistry, an umbrella view of the myriad of classes of materials that make renewable energy technologies work. They are poised to facilitate the transition of non-renewable and unsustainable energy systems of the past into renewable and sustainable energy systems of the future. It is a story that often begins in chemistry laboratories with the discovery of new energy materials. Yet, to displace materials in existing energy technologies with new ones, depends not only on the ability to design and engineer a superior set of performance metrics for the material and the technology but also the requirement to meet a demanding collection of economic, regulatory, social, policy, environmental and sustainability criteria. Disruption in the traditional way of discovering materials is coming with the emergence of artificial intelligence, machine learning and robotic automation designed to accelerate the well-established discovery process, massive libraries of materials can be evaluated and the possibilities are endless. This book provides a perspective on the application of these new technologies to this field as well as an overview of energy materials discovery in the broader techno-economic and social context. Any budding researcher or more experienced materials scientist will find a guide to a fascinating story of discovery and emerge with a vision of what is next.
Download or read book Primary Photoexcitations in Conjugated Polymers written by Niyazi Serdar Sariciftci and published by World Scientific Publishing Company Incorporated. This book was released on 1997-01-01 with total page 621 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemical Modelling written by Michael Springborg and published by Royal Society of Chemistry. This book was released on 2021-04-14 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical modelling covers a wide range of disciplines and this book is the first stop for any materials scientist, biochemist, chemist or molecular physicist wishing to acquaint themselves with major developments in the applications and theory of chemical modelling. Containing both comprehensive and critical reviews, it is a convenient reference to the current literature. Coverage includes, but is not limited to, isomerism in polyoxometalate chemistry, modelling molecular magnets, molecular modelling of cyclodextrin inclusion complexes and graphene nanoribbons heterojunctions.
Download or read book Charge and Energy Transfer Dynamics in Molecular Systems written by Volkhard May and published by Wiley-VCH. This book was released on 2000-02-22 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing a unified description of different transfer phenomena in molecular systems, this volume serves as an introduction for graduate students and researchers. The authors manage to bridge the regimes of coherent and dissipative dynamics and thus establish the connection between classic rate theories and modern treatments of ultrafast phenomena. Starting from microscopic models, the common features of the different transfer processes are highlighted. The applications range from vibrational energy flow in large polyatomics, the motion of protons in solution, up to the concerted dynamics of electronic and nuclear degrees of freedom in molecules and molecular aggregates.
Download or read book Photovoltaic Modeling Handbook written by Monika Freunek Müller and published by John Wiley & Sons. This book was released on 2018-08-03 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides the reader with a solid understanding of the fundamental modeling of photovoltaic devices. After the material independent limit of photovoltaic conversion, the readers are introduced to the most well-known theory of "classical" silicon modeling. Based on this, for each of the most important PV materials, their performance under different conditions is modeled. This book also covers different modeling approaches, from very fundamental theoretic investigations to applied numeric simulations based on experimental values. The book concludes wth a chapter on the influence of spectral variations. The information is supported by providing the names of simulation software and basic literature to the field. The information in the book gives the user specific application with a solid background in hand, to judge which materials could be appropriate as well as realistic expectations of the performance the devices could achieve.
Download or read book Atomistic Simulations to Predict Semiconducting Polymer Blend Morphology Effect on Charge Transport written by Puja Agarwala and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conjugated polymer blend morphology dictates performance of many organic electronic devices, including electrochemical transistors, light-emitting diodes, and solar cells. In organic photovoltaics (OPVs), electronically active layer morphology of polymer and oligomer bulk-heterojunction influences charge transport and exciton dissociation properties and governs device performance. Yet a faithful representation of the blend interface and local morphology is lacking. In principle, molecular dynamics simulation can represent these blends. However, semiconducting polymers with aromatic rings are large, stiff, and slowly relaxing, which makes equilibration challenging. We develop a new coarse-graining (CG) method, which improves simulation efficiency ten-fold by representing aromatic rings as rigidly bonded moieties, in which we represent several atoms as virtual sites. P3HT simulations with virtual site coarse graining show that the polymer persistence length and the melt density agrees with experimental results. An agreement between scattering extracted from P3HT simulations and wide-angle X-ray scattering experiment validates the simulation local morphology. In the amorphous phase, the scattering results in two wide peaks: the low q peak originates from interchain backbone correlations, and the high q peak originates from interchain side group correlations. We use the virtual site method to characterize the morphology of a typical OPV blend: P3HT (donor) and O-IDTBR (acceptor) and their pure phases. The blend morphology shows that moieties with solubilizing side-groups have fewer electronic contacts because of steric hindrance. On slow cooling, the fast simulation method enables us to observe crystallization, which occurs more readily in pure P3HT than in the blend. Simulations of a low molecular weight P3HT with O-IDTBR represent the local structures of small mixed regions. To describe a de-mixed blend interface, we need the Flory-Huggins [chi] parameter. We develop a "push-pull" technique to measure [chi], which applies robustly to polymer blends of any architecture. The method applies equal and opposite potentials to polymers in a blend to induce a concentration gradient, which is more pronounced for polymers with repulsive interactions ([chi]>0). Chain flexibility plays an important role as stiffer polymers require more energy to induce concentration gradient. We validate the method by blends of bead-spring chains with varying flexibility and PE/PEO blend. The [chi] evaluated from "push-pull'' methods are comparable to the results from previously developed "morphing'' method. We obtain a comprehensive view of the OPV blend morphology by combining local structures from our CG representation and the [chi] parameter from the "push-pull" technique. The [chi] calculated for a blend of P3HT and O-IDTBR shows that the blend follows an upper critical solution temperature behavior and predicts the critical molecular weight of P3HT for phase separation. An amorphous blend of P3HT and O-IDTBR forms an interface of a few nanometers. In contrast, the presence of a crystal acceptor crystallizes the donor polymer on its surface, forming a sharp interface. Crystallization reduces overall contact between donor and acceptor but increases face-on contact, which is important for exciton dissociation. O-IDTBR solubilized in P3HT may also aid in exciton dissociation; however, the polarons formed can not percolate to the acceptor rich region with only 15% solubility and may result in recombination losses. Much higher solubility is required for charge percolation to occur. However, increasing the acceptor solubility in the donor phase may cause crystal structure disruption. A polaron formed by exciton dissociation hops from one chain to another, and the polaron hopping rate depends on the electronic coupling between neighboring molecules governed by their local structures. Electronic coupling of a few thousand P3HT monomer pairs from an amorphous melt shows that strong contacts with high electronic coupling are rare. Feature selection in machine learning helps identify the most important feature for strong contact. The key geometric features closely relate to coherent overlap between HOMO wavefunctions on nearby moieties for hole transport. We develop a machine learning model to evaluate electronic coupling distribution with morphological changes. Slow cooling induces crystallization in P3HT and increases the number of strong contacts. Furthermore, we provide a future direction to understand the high performing organic photovoltaic blend morphology and relate the morphology to their electronic properties. The structure-property relationship will aid in developing rational design of conjugated polymers for efficient organic photovoltaic application.
Download or read book Modern Methods for Theoretical Physical Chemistry of Biopolymers written by Evgeni Starikov and published by Elsevier. This book was released on 2011-08-11 with total page 605 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modern Methods for Theoretical Physical Chemistry of Biopolymers provides an interesting selection of contributions from an international team of researchers in theoretical chemistry. This book is extremely useful for tackling the complicated scientific problems connected with biopolymers' physics and chemistry. The applications of both the classical molecular-mechanical and molecular-dynamical methods and the quantum chemical methods needed for bridging the gap to structural and dynamical properties dependent on electron dynamics are explained. Also included are ways to deal with complex problems when all three approaches need to be considered at the same time. The book gives a rich spectrum of applications: from theoretical considerations of how ATP is produced and used as ‘energy currency’ in the living cell, to the effects of subtle solvent influence on properties of biopolymers and how structural changes in DNA during single-molecule manipulation may be interpreted. · Presents modern successes and trends in theoretical physical chemistry/chemical physics of biopolymers · Topics covered are of relevant importance to rapidly developing areas in science such as nanotechnology and molecular medicine · Quality selection of contributions from renowned scientists in the field
Download or read book Charge Transport in Disordered Solids with Applications in Electronics written by Sergei Baranovski and published by John Wiley & Sons. This book was released on 2006-08-14 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of charge conduction in disordered materials is a rapidly evolving area owing to current and potential applications of these materials in various electronic devices This text aims to cover conduction in disordered solids from fundamental physical principles and theories, through practical material development with an emphasis on applications in all areas of electronic materials. International group of contributors Presents basic physical concepts developed in this field in recent years in a uniform manner Brings up-to-date, in a one-stop source, a key evolving area in the field of electronic materials
