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Understanding Morphology And Anisotropic Charge Transport In Conjugated Semi Crystalline Polymers
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Book Synopsis Understanding Morphology and Anisotropic Charge Transport in Conjugated, Semi-crystalline Polymers by : Kim Tremel
Download or read book Understanding Morphology and Anisotropic Charge Transport in Conjugated, Semi-crystalline Polymers written by Kim Tremel and published by . This book was released on 2014 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Understanding Microstructure and Charge Transport in Semicrystalline Polythiophenes by : Leslie Hendrix Jimison
Download or read book Understanding Microstructure and Charge Transport in Semicrystalline Polythiophenes written by Leslie Hendrix Jimison and published by Stanford University. This book was released on 2011 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconducting polymers are a promising class of organic electronic materials, with the potential to have a large impact in the field of macroelectronics. In this thesis, we focus on understanding the relationship between microstructure and charge transport in semicrystalline polythiophenes. A method is presented for the measurement of complete pole figures of polymer thin films using an area detector, allowing for the first time quantitative characterization of crystalline texture and degree of crystallinity. Thin film transistors are used to measure electrical characteristics, and charge transport behavior is modeled according to the Mobility Edge (ME) model. These characterization methods are first used to investigate the effect of substrate surface treatment and thermal annealing on the microstructure of polythiophene thin films, and the effect of microstructural details on charge transport. Next, we investigate the semicrystalline microstructure in confined polythiophene films. Pole figures are used to quantify a decrease in the degree of crystallinity of films with decreasing thickness, accompanied by an improvement in crystalline texture. Next, we investigate the influence of the degree of regioregularity, molecular weight and the processing solvent on microstructure (degree of crystallinity and texture) and charge transport in high mobility P3HT thin films. Surprisingly, when processing conditions are optimized, even a polymer with moderate regioregularity can form a highly textured film with high charge carrier mobility. Finally, we use films of P3HT with engineered, anisotropic in-plane microstructure to understand the importance and mechanism of transport across grain boundaries in these semicrystalline films. Results from this study provide the first experimental evidence for the application of a percolation model for charge transport in high molecular weight semicrystalline polymer semiconductors. Understanding how characteristics of the polymer as well as details of the processing conditions can affect the film microstructure and device performance is important for future materials design and device fabrication.
Book Synopsis Morphology and Charge Transport in Conjugated Polymers by : Victor Rühle
Download or read book Morphology and Charge Transport in Conjugated Polymers written by Victor Rühle and published by . This book was released on 2010 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Morphology and Charge Transport in Conjugated Polymers by :
Download or read book Morphology and Charge Transport in Conjugated Polymers written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To assist rational compound design of organic semiconductors, two problems need to be addressed. First, the material morphology has to be known at an atomistic level. Second, with the morphology at hand, an appropriate charge transport model needs to be developed in order to link charge carrier mobility to structure.rnrnThe former can be addressed by generating atomistic morphologies using molecular dynamics simulations. However, the accessible range of time- and length-scales is limited. To overcome these limitations, systematic coarse-graining methods can be used. In the first part of the thesis, the Versatile Object-oriented Toolkit for Coarse-graining Applications is introduced, which provides a platform for the implementation of coarse-graining methods. Tools to perform Boltzmann inversion, iterative Boltzmann inversion, inverse Monte Carlo, and force-matching are available and have been tested on a set of model systems (water, methanol, propane and a single hexane chain). Advantages and problems of each specific method are discussed.rnrnIn partially disordered systems, the second issue is closely connected to constructing appropriate diabatic states between which charge transfer occurs. In the second part of the thesis, the description initially used for small conjugated molecules is extended to conjugated polymers. Here, charge transport is modeled by introducing conjugated segments on which charge carriers are localized. Inter-chain transport is then treated within a high temperature non-adiabatic Marcus theory while an adiabatic rate expression is used for intra-chain transport. The charge dynamics is simulated using the kinetic Monte Carlo method.rnrnThe entire framework is finally employed to establish a relation between the morphology and the charge mobility of the neutral and doped states of polypyrrole, a conjugated polymer. It is shown that for short oligomers, charge carrier mobility is insensitive to the orientational molecular ordering and is deter.
Book Synopsis Understanding Microstructure and Charge Transport in Semicrystalline Polythiophenes by : Leslie Hendrix Jimison
Download or read book Understanding Microstructure and Charge Transport in Semicrystalline Polythiophenes written by Leslie Hendrix Jimison and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconducting polymers are a promising class of organic electronic materials, with the potential to have a large impact in the field of macroelectronics. In this thesis, we focus on understanding the relationship between microstructure and charge transport in semicrystalline polythiophenes. A method is presented for the measurement of complete pole figures of polymer thin films using an area detector, allowing for the first time quantitative characterization of crystalline texture and degree of crystallinity. Thin film transistors are used to measure electrical characteristics, and charge transport behavior is modeled according to the Mobility Edge (ME) model. These characterization methods are first used to investigate the effect of substrate surface treatment and thermal annealing on the microstructure of polythiophene thin films, and the effect of microstructural details on charge transport. Next, we investigate the semicrystalline microstructure in confined polythiophene films. Pole figures are used to quantify a decrease in the degree of crystallinity of films with decreasing thickness, accompanied by an improvement in crystalline texture. Next, we investigate the influence of the degree of regioregularity, molecular weight and the processing solvent on microstructure (degree of crystallinity and texture) and charge transport in high mobility P3HT thin films. Surprisingly, when processing conditions are optimized, even a polymer with moderate regioregularity can form a highly textured film with high charge carrier mobility. Finally, we use films of P3HT with engineered, anisotropic in-plane microstructure to understand the importance and mechanism of transport across grain boundaries in these semicrystalline films. Results from this study provide the first experimental evidence for the application of a percolation model for charge transport in high molecular weight semicrystalline polymer semiconductors. Understanding how characteristics of the polymer as well as details of the processing conditions can affect the film microstructure and device performance is important for future materials design and device fabrication.
Book Synopsis Structure and Electronic Property Relationships in Chemically Doped Semiconducting Polymers and Polymer Photovoltaics by : Taylor Aubry-Komin
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.
Book Synopsis Polymer Morphology and Transport by : H. J. Sha
Download or read book Polymer Morphology and Transport written by H. J. Sha and published by . This book was released on 1988 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research was to gain an understanding of the transport/morphology relationships in semi-crystalline polymers. It was hoped that this research would lead to the development of inexpensive high barrier materials with desirable mechanical properties. Briefly we have found that: 1) Uniaxial drawing is an extremely effective way to increase the barrier of semicrystalline films. For HDPE with a 20x draw, barrier improves by a factor of = 500 for carbon tetrachloride; = 50-100 for diatomic oxygen and carbon dioxide and = 25 for helium. 2) The mechanism for this improvement is less clearly understood; however it is not due to major changes in percentages crystallinity or an increase in amorphous density. At this stage it appears to be due to a reduction in amorphous chain mobility. Keywords: Diffusion; Morphology; Sorption; Draw ratio; HDPE(High Density Polyethylene). (aw).
Book Synopsis Chain Conformation and Disorder in High Mobility Semiconducting Polymers by : Rodrigo Javier Noriega-Manez
Download or read book Chain Conformation and Disorder in High Mobility Semiconducting Polymers written by Rodrigo Javier Noriega-Manez and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A critical step to understanding charge transport in complex systems is being able to characterize them accurately and extensively. In particular, the microstucture of conjugated polymers exhibits a coexistence of ordered and amorphous regions, with the size of the ordered regions being smaller than the length of individual polymer chains. In order to study the ordered regions we use advanced X-ray diffraction analysis in combination with computational modeling and measurements of optical and electrical properties. It was possible to uncover fundamental relationships between short-range order in pi-aggregates, aggregate connectivity and macroscopic charge transport in semiconducting polymers. An unusually high and materials-independent amount of paracrystalline disorder was found in all high-performing polymers. Computer simulations and analytical models made the connection between fluctuations in molecular arrangement and electronic traps. Charge transport studies elucidated the predominant role of paracrystallites in semicrystalline and strongly disordered polymer films. The other component of the microstructure -- the amorphous regions -- deserves our attention as well since aggregate connectivity depends on it. A model for charge transport in strongly disordered polymers was developed for this reason. The morphology of individual polymer chains can be determined by well-known statistical models. Likewise, the electronic coupling between units along a polymer chain and on different molecules can be determined by Marcus theory. Combining knowledge from both areas into an analytical and computational model that incorporates the structural and electronic properties of polymers, it is possible to explain observations that previously relied on phenomenological models. The multi-scale behavior of charges in these materials (high mobility at short scales, low mobility at long scales) is naturally described with this framework. Additionally, the dependence of mobility with electric field and temperature is explained in terms of conformational fluctuations and correlations. Bringing all these concepts together it is possible to provide a more complete description of the way in which charges move in conjugated polymers, a set of materials that occupies an intermediate region between ordered and disordered systems, with a great amount of complexity at various length scales. Doing so will facilitate the feedback cycle between molecular design, microstructure optimization, and device performance.
Book Synopsis Morphological and Energetic Effects on Charge Transport in Conjugated Polymers and Polymer-nanowire Composites by : Zhiming Liang
Download or read book Morphological and Energetic Effects on Charge Transport in Conjugated Polymers and Polymer-nanowire Composites written by Zhiming Liang and published by . This book was released on 2018 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Understanding the Morphological Effects of Self-Assembly and Molecular Doping in Semiconducting Polymers by : Patrick Yee
Download or read book Understanding the Morphological Effects of Self-Assembly and Molecular Doping in Semiconducting Polymers written by Patrick Yee and published by . This book was released on 2019 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconducting polymers are a versatile class of materials used for a variety of electronic applications. They are a cheap source of material relative to their inorganic counterparts, are flexible, and with solution processing, are easily scalable However, they are intrinsically poor conductors, which can result in low device efficiencies and shorter carrier lifetimes. The conductivity can be improved using a variety of methods, including controlling the morphology to improve carrier transport or introducing charge carriers using chemical dopants. In this dissertation, we describe experiments that use a combination of X-ray and neutron scattering techniques to understand how we can use morphology in semiconducting polymers to improve their charge transport properties. The first part of this dissertation focuses on the design of an amphiphilic conjugated polyelectrolyte model system to control the aggregation of polymer chains in solution, with the goal of straightening chains to reduce carrier trap sites caused by kinks that disrupt the -conjugation. After showing good control of the nanoscale morphology in a well-defined, ideal system in solution, we then look at the controllably improving the electron transfer process in an actual organic photovoltaic (OPV) device. We then look to control and improve the electron transfer process in full organic photovoltaic devices. We show that using sequential processing, where the polymer and fullerene are deposited in two separate steps, we can control the device level mixing of polymer and fullerene. We end with a discussion of studies focused on the morphological effects of molecular doping of semiconducting polymers. Using small molecule dopants, we show that with SqP, the polymer morphology is maintained as compared to conventional blend casting (BC) method. This allows more dopant to incorporate into thin films, further increasing the conductivity. Thereafter, we focus on how SqP provides the opportunity to tune the polymer morphology prior to doping and investigate how controlling the polymer crystallinity affects the optical and electronic properties in its doped state. Using statistical copolymers, we investigate the effect of polymer crystallinity and energy level offset between polymer and dopant. Finally, we conclude with a study on how the interplay between polymer chain ordering and the location of the dopant counterion in the lattice controls polymer conductivity. Overall, these results emphasize the importance of understanding and controlling the morphology of semiconducting polymers on multiple length-scales.
Book Synopsis Microstructure and Charge Transport in Conjugated Polymers by : Chenchen Wang
Download or read book Microstructure and Charge Transport in Conjugated Polymers written by Chenchen Wang and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Conjugated polymers have attracted broad interest in the past few decades due to their potential applications in organic light emitting diodes, low-cost flexible circuits, biosensors and photovoltaics. Because of their semicrystalline nature, the spatial arrangement of the crystallites and the disordered regions would have strong impact on the charge transport properties of conjugated polymer thin films. Therefore, in this presentation, I will focus on understanding the relationship between the film's morphology, microstructure and electronic properties, and how to fabricate desired structure to achieve devices with novel electronic performance. In the first part of the presentation, I will show that the device's electronic performance can be greatly improved by engineering its structure in solution based fabrication process. The binary blends of regioregular (rr) and regiorandom (RRa) P3HT are used to form desired FET structures. X-ray diffraction of the blended films is consistent with a vertically-separated structure, with rr-P3HT preferentially crystallizing at the semiconductor/dielectric interface. Because of the ultra-thin rr-P3HT active layer at the interface, these devices not only preserve high mobility in rr-P3HT, but also eliminate the short channel effects due to bulk currents, suggesting a new route to fabricate high performance, short-channel and reliable organic electronic devices. After that, I will discuss the microstructural origin of high mobility in poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophenes) (PBTTT) thin-film transistors (TFTs). Charge transport in PBTTT TFTs is analyzed with a mobility edge (ME) model and compared to these in poly(3-hexylthiophene) (P3HT) TFTs. With TEM characterization of delaminated films, we conclude that the improved performance of PBTTT compared to P3HT is not due to a low trap density but rather to a high mobility in the crystallites. Finally, the third part of the presentation will focus on optical characterization of doping in conjugated polymers. UV-vis and IR absorption spectra of 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) doped P3HT at different doping concentration are measured and analyzed. Absorption peaks from P3HT, F4TCNQ, F4TCNQ anion and P3HT polaron/bipolarons are identified and decomposed. The P3HT polaron/bipolarons cross sections in UV-vis region are estimated, which can be used to evaluate doping efficiency in this material.
Book Synopsis Conjugated Polymers by : John R. Reynolds
Download or read book Conjugated Polymers written by John R. Reynolds and published by CRC Press. This book was released on 2019-03-25 with total page 832 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers properties, processing, and applications of conducting polymers. It discusses properties and characterization, including photophysics and transport. It then moves to processing and morphology of conducting polymers, covering such topics as printing, thermal processing, morphology evolution, conducting polymer composites, thin films
Book Synopsis P3HT Revisited – From Molecular Scale to Solar Cell Devices by : Sabine Ludwigs
Download or read book P3HT Revisited – From Molecular Scale to Solar Cell Devices written by Sabine Ludwigs and published by Springer. This book was released on 2014-11-13 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Advances in Polymer Science presents critical reviews of the present and future trends in polymer and biopolymer science. It covers all areas of research in polymer and biopolymer science including chemistry, physical chemistry, physics, material science. The thematic volumes are addressed to scientists, whether at universities or in industry, who wish to keep abreast of the important advances in the covered topics. Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist. Review articles for the individual volumes are invited by the volume editors. Single contributions can be specially commissioned. Readership: Polymer scientists, or scientists in related fields interested in polymer and biopolymer science, at universities or in industry, graduate students
Download or read book Indian Journal of Chemistry written by and published by . This book was released on 2004 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Handbook of Conducting Polymers, Fourth Edition - 2 Volume Set by : John R. Reynolds
Download or read book Handbook of Conducting Polymers, Fourth Edition - 2 Volume Set written by John R. Reynolds and published by CRC Press. This book was released on 2019-11-14 with total page 1488 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last 10 years there have been major advances in fundamental understanding and applications and a vast portfolio of new polymer structures with unique and tailored properties was developed. Work moved from a chemical repeat unit structure to one more based on structural control, new polymerization methodologies, properties, processing, and applications. The 4th Edition takes this into account and will be completely rewritten and reorganized, focusing on spin coating, spray coating, blade/slot die coating, layer-by-layer assembly, and fiber spinning methods; property characterizations of redox, interfacial, electrical, and optical phenomena; and commercial applications.
Book Synopsis Flexible Flat Panel Displays by : Gregory Crawford
Download or read book Flexible Flat Panel Displays written by Gregory Crawford and published by John Wiley & Sons. This book was released on 2005-08-19 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flexible displays are currently one of the most researched topics within the flat panel display community. They promise to change our display-centric world by replacing bulky rigid devices with those that are paper-thin and can be rolled away or folded up when not in use. The field of flexible flat panel displays is truly unique in the sense that it is interdisciplinary to the display community, combining basic principles from nearly all engineering and science disciplines. Organized to bring the reader from the component level, through display system and assembly, to the possible manufacturing routes Flexible Flat Panel Displays: * outlines the underlying scientific theory required to develop flexible display applications; * addresses the critical issues relating to the convergence of technologies including substrates, conducting layers, electro-optic materials and thin-film transistors; * provides guidance on flexible display manufacturing; and * presents market information and a chapter dedicated to future market trends of flexible flat panel displays. Flexible Flat Panel Displays is an essential tool for scientists, engineers, designers and business and marketing professionals working at all levels of the display industry. Graduate students entering the field of display technology will also find this book an excellent reference. The Society for Information Display (SID) is an international society, which has the aim of encouraging the development of all aspects of the field of information display. Complementary to the aims of the society, the Wiley-SID series is intended to explain the latest developments in information display technology at a professional level. The broad scope of the series addresses all facets of information displays from technical aspects through systems and prototypes to standards and ergonomics
Download or read book Polymer Morphology written by Qipeng Guo and published by John Wiley & Sons. This book was released on 2016-05-16 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: With a focus on structure-property relationships, this book describes how polymer morphology affects properties and how scientists can modify them. The book covers structure development, theory, simulation, and processing; and discusses a broad range of techniques and methods. • Provides an up-to-date, comprehensive introduction to the principles and practices of polymer morphology • Illustrates major structure types, such as semicrystalline morphology, surface-induced polymer crystallization, phase separation, self-assembly, deformation, and surface topography • Covers a variety of polymers, such as homopolymers, block copolymers, polymer thin films, polymer blends, and polymer nanocomposites • Discusses a broad range of advanced and novel techniques and methods, like x-ray diffraction, thermal analysis, and electron microscopy and their applications in the morphology of polymer materials
