Download or read book Structure Property Relationships in Semiconducting Polymers and Small Molecules Probed by Synchrotron X ray Methods written by Gregory M. Su and published by . This book was released on 2015 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic semiconductors are an exciting class of materials that have potential to produce low-cost, printable, and flexible electronic devices. Moving to the next generation of organic semiconductors that will result in greater efficiency requires advancements in the areas of materials chemistry, molecular assembly, predictive modelling, and device optimization. Here, we focus on morphology and demonstrate how it is linked to each of these areas. Understanding the connections among chemistry, thin film microstructure, and charge transport remains a major challenge in the field. We examined materials systems relevant to organic solar cells, memory devices, and transistors, with a focus on synchrotron-based X-ray techniques. For a blend of a polymer and small molecule, applicable to solar cells, control of molecular orientation in the small molecule is especially important for non-fullerene based molecules that exhibit anisotropic charge transport. In ferroelectric-semiconductor polymer blends used in organic memory, improved control over phase separation length scales is achieved by altering the chemistry of the semiconducting polymer to tune polymer-polymer interactions. Complementary simulations can facilitate characterization of organic semiconductors. First-principles predictions of X-ray absorption spectroscopy are applied to semiconducting polymers, and prove critical for understanding complex experimental data related to molecular orientation and electronic structure in general. Overall, these studies provide insights into key factors that should be considered in the development of new organic semiconductors.
Download or read book Understanding Structure Function Relationships in Semiconducting Polymer Morphology written by Katharine Adele Winchell and published by . This book was released on 2020 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconducting polymers are a promising class of materials for many organic electronic applications because of their structural tunability, low cost, and solution processability, which allows for easy scale-up. However, semiconducting polymers have intrinsically poor conductivity which limits their performance in all device applications. Polymer conductivity can be improved either by adding mobile carriers to the system or by manipulating the system to make the polymer chains more ordered on a local and global scale. This thesis studies both of these methods with a goal of improving polymer conductivity, while simultaneously seeking to understand how changes in morphology affect both local and global polymer properties. We used a variety of X-ray and neutron scattering techniques to characterize polymer structure, coupled with electronic and spectroscopic experiments to gain a full picture of polymer structure-function relationship. The first half of this thesis studies the structural changes that result from introducing a molecular dopant and additional charge carriers into the polymer network, and how those change control the resulting electronic and optical properties. We start by studying a novel class of large, redox-tunable dodecaborane-based dopants. From these studies we are able to determine how redox potential controls both dopant infiltration into polymer films and the resulting film structure, providing insight into the relationship between structure and conductivity for doped conjugated polymer systems. Using traditional small-molecule dopants, we also studied various doping methods to assess scalability and application to thick polymer films. The second half of this thesis presents studies on various methods to manipulate the local morphology of polymer chains to increase their overall order. We first used an aqueous amphiphilic self-assembly system where we developed structural design rules for order assembly and demonstrate that they can be used to create polymer system that show straightened chains when self-assembled. Next, we explored a set of block-copolymers whose co-crystallization properties could be changed using the polymer molecular weight; here we show that crystallization behavior directly affects conductivity. Lastly, we studied a host-guest system of polymers aligned in straight silica mesoporous, with a goal of using confinement to understand the interplay between polymer microstructure and aggregation.
Download or read book Structure and Electronic Property Relationships in Chemically Doped Semiconducting Polymers and Polymer Photovoltaics written by Taylor Aubry-Komin and published by . This book was released on 2019 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work is focused on understanding how molecular-level structural control can improve charge carrier properties in -conjugated polymers. Conjugated polymers are characterized by extended conjugation along their backbone, making them intrinsically semiconducting materials that are of interest for a wide variety of flexible, thin-film electronic applications. Polymeric semiconductors possess advantages over inorganic materials such as being lightweight, low-cost and solution processable. However, due the disordered nature of conjugated polymers and their anisotropic transport, charge carrier dynamics can be highly sensitive to structural effects. The first chapter of this dissertation gives an introduction to conjugated polymers and their relevant applications as well as how tuning morphology and doping level can influence their charge carrier properties. The second introduces a technique, known as sequential processing (SqP), that affords control over polymer domain orientation when preparing polymer films as the active layer in optoelectronic devices. We show that conventional processing methods lead to disordered, isotropic polymer networks. By contrast, SqP can be used to preserve the preferred face-on chain orientation seen with some polymer materials, yielding advantages for photovoltaics and other devices via increased vertical hole mobility. Chapter 3 turns to molecular doping of conjugated polymers and studies the effects of a bulky boron cluster dopant used to modify the charge transport properties of conjugated polymers. The design of the dopant is such that it sterically protects core-localized electron density, resulting in shielding of the electron from holes produced on the polymer. This allows the charge carriers to be highly delocalized, as confirmed both spectroscopically and by AC-Hall effect measurements. The dopants allow for high carrier mobilities to be achieved even for non-crystalline polymers. The implication is that the counterion distance is the most important factor needed to produce high carrier mobility in conjugated polymers. In the last chapter, we study a series of boron cluster dopants in which the redox potential is tuned over a large range but the anion distance is fixed. In the last chapter, we study a series of boron cluster dopants in which the redox potential is tuned over a large range but the anion distance is fixed. This allows us to disentangle the effects of energetic offset in doping on the production of free carriers. We find that the redox potential not only affects the generation of free carriers, but also the infiltration of dopants into the polymer films.
Download or read book Structure function Relationships in Semiconducting Polymers written by Luke Balhorn and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Improving knowledge of structure-function relationships in semiconducting polymers will help design new materials that unlock new applications. This work harnesses recent advances in transmission electron microscopy of soft materials to study length scales of microstructure in these materials that have previously been difficult to probe. Further, it combines electron microscopy with structural and charge transport simulations to study the effects of mesoscale defects on charge transport in highly ordered semicrystalline polymers. Spatially resolved nanodiffraction (4D-STEM) is used to create maps of chain direction and local order in conjugated polymers. Simulations are then built upon this experimental map, first by generating molecular geometries consistent with diffraction data, then by tracking the paths of test charges across the region. A case study in this combined method is conducted using the polymer PBTTT. Short-range charge transport is shown to be more chaotic than is often pictured, with the drift velocity accounting for a small portion of overall charge motion. Local transport is sensitive to the alignment and geometry of polymer chains. At longer length scales, the curves of this PBTTT microstructure funnel charges to specific regions, creating inhomogeneous charge distributions. While alignment generally improves mobility, these funneling effects limit the overall efficiency of charge transport. The structure is modified \textit{in silico} to explore possible design rules, showing chain stiffness and alignment to be beneficial while local homogeneity has no positive effect. These observations provide direct guidance for improving mesoscale structure for future materials.
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 Synchrotron Radiation in Materials Science written by Chunhai Fan and published by John Wiley & Sons. This book was released on 2018-05-29 with total page 846 pages. Available in PDF, EPUB and Kindle. Book excerpt: Meeting the long-felt need for in-depth information on one of the most advanced material characterization methods, a top team of editors and authors from highly prestigious facilities and institutions covers a range of synchrotron techniques that have proven useful for materials research. Following an introduction to synchrotron radiation and its sources, the second part goes on to describe the various techniques that benefit from this especially bright light, including X-ray absorption, diffraction, scattering, imaging, and lithography. The thrid and final part provides an overview of the applications of synchrotron radiation in materials science. bridging the gap between specialists in synchrotron research and material scientists, this is a unique and indispensable resource for academic and industrial researchers alike.
Download or read book Organic Thermoelectric Materials written by Zhiqun Lin and published by Royal Society of Chemistry. This book was released on 2019-10-18 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarises the significant progress made in organic thermoelectric materials, focusing on effective routes to minimize thermal conductivity and maximize power factor.
Download or read book Visualizing Chemistry written by National Research Council and published by National Academies Press. This book was released on 2006-06-01 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientists and engineers have long relied on the power of imaging techniques to help see objects invisible to the naked eye, and thus, to advance scientific knowledge. These experts are constantly pushing the limits of technology in pursuit of chemical imagingâ€"the ability to visualize molecular structures and chemical composition in time and space as actual events unfoldâ€"from the smallest dimension of a biological system to the widest expanse of a distant galaxy. Chemical imaging has a variety of applications for almost every facet of our daily lives, ranging from medical diagnosis and treatment to the study and design of material properties in new products. In addition to highlighting advances in chemical imaging that could have the greatest impact on critical problems in science and technology, Visualizing Chemistry reviews the current state of chemical imaging technology, identifies promising future developments and their applications, and suggests a research and educational agenda to enable breakthrough improvements.
Download or read book Synchrotron Radiation Applications written by Xinyi Zhang and published by . This book was released on 2018 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The book contains the latest synchrotron-based techniques and research results. All contributors are specialists or leading scientists in their fields. The book includes new techniques and methods that will potentially get wider applications in various disciplines"--
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1983 with total page 1368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Soft Matter written by Ian W. Hamley and published by John Wiley & Sons. This book was released on 2013-03-18 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an introduction to this exciting and relativelynew subject with chapters covering natural and synthetic polymers,colloids, surfactants and liquid crystals highlighting the many andvaried applications of these materials. Written by an expert in thefield, this book will be an essential reference for people workingin both industry and academia and will aid in understanding of thisincreasingly popular topic. Contains a new chapter on biological soft matter Newly edited and updated chapters including updated coverageof recent aspects of polymer science. Contain problems at the end of each chapter to facilitateunderstanding
Download or read book Faculties Publications and Doctoral Theses in Chemistry and Chemical Engineering at United States Universities written by American Chemical Society. Committee on Professional Training and published by . This book was released on 1991 with total page 1646 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Polymer Colloids written by Rodney Priestley and published by Royal Society of Chemistry. This book was released on 2019-12-02 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: Academic and industrial research around polymer-based colloids is huge, driven both by the development of mature technologies, e.g. latexes for coatings, as well as the advancement of new materials and applications, such as building blocks for 2D/3D structures and medicine. Edited by two world-renowned leaders in polymer science and engineering, this is a fundamental text for the field. Based on a specialised course by the editors, this book provides the reader with an invaluable single source of reference. The first section describes formation, explaining basic properties of emulsions and dispersion polymerization, microfluidic approaches to produce polymer-based colloids and formation via directed self-assembly. The next section details characterisation methodologies from microscopy and small angle scattering, to surface science and simulations. The final chapters close with applications, including Pickering emulsions and molecular engineering for materials development. A comprehensive guide to polymer colloids, with contributions by leaders in their respective areas, this book is a must-have for researchers and practitioners working across polymers, soft matter and chemical and molecular engineering.
Download or read book Materials Chemistry written by Bradley D. Fahlman and published by Springer. This book was released on 2018-08-28 with total page 817 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 3rd edition of this successful textbook continues to build on the strengths that were recognized by a 2008 Textbook Excellence Award from the Text and Academic Authors Association (TAA). Materials Chemistry addresses inorganic-, organic-, and nano-based materials from a structure vs. property treatment, providing a suitable breadth and depth coverage of the rapidly evolving materials field — in a concise format. The 3rd edition offers significant updates throughout, with expanded sections on sustainability, energy storage, metal-organic frameworks, solid electrolytes, solvothermal/microwave syntheses, integrated circuits, and nanotoxicity. Most appropriate for Junior/Senior undergraduate students, as well as first-year graduate students in chemistry, physics, or engineering fields, Materials Chemistry may also serve as a valuable reference to industrial researchers. Each chapter concludes with a section that describes important materials applications, and an updated list of thought-provoking questions.
Download or read book Spectroscopy of Polymers written by J.L. Koenig and published by Elsevier. This book was released on 1999-09-16 with total page 509 pages. Available in PDF, EPUB and Kindle. Book excerpt: This revised and updated Second Edition of the best-selling reference/text is essential reading for students and scientists who seek a thorough and practical introduction to the field of polymer spectroscopy. Eleven chapters cover the fundamental aspects and experimental applications of the primary spectroscopic methods. The advantages and disadvantages of the various techniques for particular polymer systems are also discussed. The goal of the author is not to make the reader an expert in the field, but rather to provide enough information about the different spectroscopic methods that the reader can determine how the available techniques can be used to solve a particular polymer problem. This Second Edition contains new and updated information on techniques in IR and NMR, as well as an all-new chapter on Mass Spectrometry.
Download or read book Main Group Metal Coordination Polymers written by Ali Morsali and published by John Wiley & Sons. This book was released on 2017-02-03 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coordination polymer is a general term used to indicate an infinite array composed of metal ions which are bridged by certain ligands among them. This incorporates a wide range of architectures including simple one-dimensional chains with small ligands to large mesoporous frameworks. Generally, the formation process proceeds automatically and, therefore, is called a self-assembly process. In general, the type and topology of the product generated from the self-assembly of inorganic metal nodes and organic spacers depend on the functionality of the ligand and valences and the geometric needs of the metal ions used. In this book the authors explain main group metal coordination polymer in bulk and nano size with some of their application, synthesis method and etc, The properties of these efficient materials are described at length including magnetism (long-range ordering, spin crossover), porosity (gas storage, ion and guest exchange), non-linear optical activity, chiral networks, reactive networks, heterogeneous catalysis, luminescence, multifunctional materials and other properties.
Download or read book Electronic Processes in Organic Semiconductors written by Anna Köhler and published by John Wiley & Sons. This book was released on 2015-06-08 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first advanced textbook to provide a useful introduction in a brief, coherent and comprehensive way, with a focus on the fundamentals. After having read this book, students will be prepared to understand any of the many multi-authored books available in this field that discuss a particular aspect in more detail, and should also benefit from any of the textbooks in photochemistry or spectroscopy that concentrate on a particular mechanism. Based on a successful and well-proven lecture course given by one of the authors for many years, the book is clearly structured into four sections: electronic structure of organic semiconductors, charged and excited states in organic semiconductors, electronic and optical properties of organic semiconductors, and fundamentals of organic semiconductor devices.
