Download or read book Understanding the Correlation Between Microscopic Morphology and Photophysical Properties of Conjugated Polymers by Optical Spectroscopy written by Liwei Wang (Chemist) and published by . This book was released on 2021 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The unique photophysical and electronic properties of conjugated polymers (CPs) make them promising candidates for applications in displays, biosensors, field-effect transistors and photovoltaic devices. The photophysical properties of CPs are strongly dependent on the chain morphology. However, the understanding of the morphology-property correlation is still obscured both due to inhomogeneities in ensemble experiments and even due to multichromophoric properties in single chain experiments. In this dissertation, we constructed a single molecule spectroscopy apparatus and home-built MATLAB code together to correlate simultaneous measurements of intensity, lifetime and spectrum to learn more about proper photophysical models to describe the properties of CPs, the effect of O2, and the role of energy transfer in CPs. Bulk experiments in mixed solvents where chain conformations can be varied were also conducted to understand the CPs from a macroscopic perspective, where chain-chain interactions also play an important role. Especially, we selected three CPs to study, Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), Poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) and Poly(9,9-dioctylfluorene-alt-biselenophene) (F8Se2). In Chapter 3, data from mixed solvent experiments are known to produce biomodal distributions of spectra where chains emitting red light are thought to be in regions where chromophore aggregation is important. We showed in single molecule experiments that MEH-PPV follows the J-aggregate model where the properties of the chromophore are closely related to the conjugation length. Despite the similarity of the single molecule spectra to those observed in the bulk, fluorescence dynamics and intensities of red emitters are similar to those of blue emitters in the single molecule case. O2 mainly causes reversible quenching ("blinking") on the single MEH-PPV chains. Unfortunately, we could not reproduce flaring observed in a previous thesis and, although we had improved N2 protection and better signal to noise (S/N) ratio, we are not sure why our results are different. In Chapter 4 where we study F8T2, we also observe two distinct types of chromophores in the bulk experiments depending on the solvent quality. The photophysical properties of the F8T2 chains were well explained by the Spano HJ model. Even though spectral lineshapes of single F8T2 chains resemble those observed in the bulk, we concluded on the basis of very different emission intensity and lifetime behavior that the origin of the emission spectra is different and could be ascribed to bent chains. We argue that the propensity to bend in the F8T2 case and what makes it different than MEH-PPV derives from the presence of five-membered rings in F8T2 and we note behavioral similarities to polythiophenes that share this property. In Chapter 5, we showed that analogous CPs F8Se2 with selenium instead of sulfur in the monomer units exhibit strongly reduced fluorescence and dramatic reduction in singlet lifetime in the bulk due to heavy atom induced intersystem crossing to the triplet. Surprisingly, however, we observe substantial fluorescence and relatively strong emission in the single chain case for F8Se2. On the basis of a red shift in the spectrum and the long lifetimes relative to the bulk, we believe that the emission we are observing in this case is primarily from a photooxidized species similar to that observed in fluorene polymers. Overall, this work is a step towards looking more carefully at the complex correlation between morphology and photophysical properties. We show that bending of single chains can mimic the spectroscopy of aggregation and that it is necessary to consider fluorescence lifetime and efficiency data to distinguish between these effects. We have also used single chain spectroscopy to look at how chain morphology plays a significant role in energy transfer. In particular, we see little evidence for energy transfer in chains deposited from good solvents in contrast to some work where chains can behave as single chromophores when deposited under conditions where chains are able to collapse. We have also introduced a new way of looking at the relative propensity of different chains within a sample to blink and/or permanently photooxidize through studies correlating intensity drops and rises with spectra"--Pages x-xii.

Download or read book Photophysical and Morphological Implications of Single strand Conjugated Polymer Folding in Solution written by and published by . This book was released on 2016 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic semiconductors have garnered substantial interest in optoelectronics, but their device performances exhibit strong dependencies on material crystallinity and packing. In an effort to understand the interactions dictating the morphological and photophysical properties of a high-performing photovoltaic polymer, PTB7, a series of short oligomers and low molecular weight polymers of PTB7 were synthesized. Chain-length dependent optical studies of these oligomers demonstrate that PTB7's low-energy visible absorption is largely due to self-aggregation-induced ordering, rather than in-chain charge transfer, as previously thought. By examining molecular weight and concentration dependent optical properties, supplemented by molecular dynamics simulations, we attribute polymeric PTB7's unique midgap fluorescence and concentration independent absorption spectrum to an interplay between low molecular weight unaggregated strands and high-molecular weight self-aggregated (folded) strands. Specifically, we propose that the onset of PTB7 self-folding occurs between 7 and 13 repeat units, but the aggregates characteristic of polymeric PTB7 only develop at lengths of ~30 repeat units. Atomistic molecular dynamics simulations of PTB7 corroborate these conclusions, and a simple relation is proposed which quantifies the free-energy of conjugated polymer folding. Lastly, this study provides detailed guidance in the design of intra- and interchain contributions to the photophysical and morphological properties of polymeric semiconductors.

Download or read book Photophysics of Conjugated Polymers written by Tieneke E. Dykstra and published by . This book was released on 2008 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Poly (para-phenylenevinylene) (PPV), and its derivatives such as poly [2-methoxy, 5-(2'-ethyl-hexoxy)-1,4-phenylene vinylene] (MEH-PPV), are typical conjugated polymers. In order to implement conjugated polymers into processable electronics technologies, we must first understand their complex photophysical properties as their efficiencies depend on the balance between exciton recombination and charge carrier formation. The inherent complexities of these materials arise from entanglement of the pi-electron system with disorder and nuclear motions of the polymer backbone. This disorder breaks the polymer chain into conformational subunits which can couple, giving rise to a set of delocalized states formed by Coulombic interactions between proximate subunits. Characteristics of PPVs include high quantum yields, non-mirror image absorption and fluorescence line shapes, and large apparent Stokes' shifts. These properties are discussed in the context of the relationships between polymer conformation, electronic structure, coupling, disorder and polymer photophysics.These important influences are often manifest in the dynamics of what happens after photoexcitation. In this work, we present 3-pulse photon echo peak shift (3PEPS) studies of conjugated polymers in both solution and film. To elucidate timescales characteristic of relaxation processes, we have simulated the 3PEPS data simultaneously with absorption and fluorescence, observing a rapid localization of the exciton in the initial ∼ 20 fs. Additional contributions to the decay of the peakshift are discussed. We also present transient anisotropy data for PPV polymers and oligomers which is compared to dynamics simulation for isolated chains of PPVs. This work demonstrates the influence of microscopic structure on ultrafast dynamics. We show that relaxation between exciton states can lead to rapid depolarization of the anisotropy, even though the spatial extent of exciton migration may be small. Generally, the connection between conformation and electronic structure is a theme throughout this thesis.

Download or read book Photophysics of Conjugated Polymers written by Tieneke Emily Dykstra and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electronic and Optical Properties of Conjugated Polymers written by William Barford and published by Oxford University Press. This book was released on 2005-06-30 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes and explains the electronic and optical properties of conjugated polymers by developing theoretical models to understand the key electronic states.

Download or read book Correlation Between Morphology and Optical Properties of Blends of Small Organic Molecules and Thermoplastic Polymers written by Kittiyaporn Singsumphan and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of the Photophysical Properties of conjugated pi conjugated Polymers written by Richard Hildner and published by . This book was released on 2008 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Conjugated Polyelectrolytes written by Bin Liu and published by John Wiley & Sons. This book was released on 2013-08-07 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first monograph to specifically focus on fundamentals and applications of polyelectrolytes, a class of molecules that gained substantial interest due to their unique combination of properties. Combining both features of organic semiconductors and polyelectrolytes, they offer a broad field for fundamental research as well as applications to analytical chemistry, optical imaging, and opto-electronic devices. The initial chapters introduce readers to the synthesis, optical and electrical properties of various conjugated polyelectrolytes. This is followed by chapters on the applications of these materials in optical sensing and imaging with emphasis on biological systems, while the final section addresses the emerging applications of conjugated polyelectrolytes in optoelectronic devices, concluding with an in-depth discussion of structure-property relationship. The editors and contributors are all pioneers and experts in this expanding field. This monograph is not only for chemists, materials scientists, and physicists, but also a unique source of knowledge for readers with scientific background interested in polyelectrolytes.

Download or read book Conjugated Polymers written by Terje A. Skotheim and published by CRC Press. This book was released on 2006-12-26 with total page 1030 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many significant fundamental concepts and practical applications have developed since the publication of the best-selling second edition of the Handbook of Conducting Polymers. Now divided into two books, the third edition continues to retain the excellent expertise of the editors and world-renowned contributors while providing superior coverage of

Download or read book Polyfluorenes written by Ullrich Scherf and published by Springer Science & Business Media. This book was released on 2008-07-29 with total page 331 pages. Available in PDF, EPUB and Kindle. Book excerpt: With this collection of short review papers we would like to present a broad overview of research on poly?uorenes and related heteroanalogues over the last two decades. The collection begins with papers on the synthesis of po- ?uorenesandrelatedpolyheteroarenes, thenreportsphotophysicalproperties of this class of conjugated polymers both at the ensemble and the single chain level, continues with a discussion of the rich solid state structures of poly?uorenes, and ?nally switches to device applications (e.g. in OLEDs). In addition, two chapters are devoted to de?ned oligo?uorenesas lowmolecular weight model systems forpoly?uorenes and also to degradation studies. We feel that this up-to-date collection will be very helpful to all polymer chemists and physicists, and will also aid graduate students interested in this fascinating and still growing area of research, since such a compact overview is only now available. All articles are presented by leading scientists in their ?elds, insuring state-of-the-art coverage of all relevant aspects. Together with the body of references this volume is meant to assist researchers in the daily lab routine. Moreover, Advances in Polymer Science, as an established series of high quality review papers, represents a very appropriate platform for our project.Wehopethatthisshortcollectionwillbeofgreatvaluebothforbeg- ners and established researchscientists inthe?eldofpoly?uorene research.

Download or read book Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications written by Srabanti Ghosh and published by John Wiley & Sons. This book was released on 2021-06-01 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: A timely overview of fundamental and advanced topics of conjugated polymer nanostructures Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications is a comprehensive reference on conjugated polymers for energy applications. Distinguished academic and editor Srabanti Ghosh offers readers a broad overview of the synthesis, characterization, and energy-related applications of nanostructures based on conjugated polymers. The book includes novel approaches and presents an interdisciplinary perspective rooted in the interfacing of polymer and synthetic chemistry, materials science, organic chemistry, and analytical chemistry. This book provides complete descriptions of conjugated polymer nanostructures and polymer-based hybrid materials for energy conversion, water splitting, and the degradation of organic pollutants. Photovoltaics, solar cells, and energy storage devices such as supercapacitors, lithium ion battery electrodes, and their associated technologies are discussed, as well. Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications covers both the fundamental topics and the most recent advances in this rapidly developing area, including: The design and characterization of conjugated polymer nanostructures, including the template-free and chemical synthesis of polymer nanostructures Conjugated polymer nanostructures for solar energy conversion and environmental protection, including the use of conjugated polymer-based nanocomposites as photocatalysts Conjugated polymer nanostructures for energy storage, including the use of nanocomposites as electrode materials The presentation of different and novel methods of utilizing conjugated polymer nanostructures for energy applications Perfect for materials scientists, polymer chemists, and physical chemists, Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications also belongs on the bookshelves of organic chemists and any other practicing researchers, academics, or professionals whose work touches on these highly versatile and useful structures.

Download or read book Conjugated Polymers written by John R. Reynolds and published by CRC Press. This book was released on 2019-03-27 with total page 718 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Fourth Edition of the Handbook of Conducting Polymers, Two-Volume Set continues to be the definitive resource on the topic of conducting polymers. Completely updated with an extensive list of authors that draws on past and new contributors, the book takes into account the significant developments both in fundamental understanding and applications since publication of the previous edition. One of two volumes comprising the comprehensive Handbook, Conjugated Polymers: Perspective, Theory, and New Materials features new chapters on the fundamental theory and new materials involved in conducting polymers. It discusses the history of physics and chemistry of these materials and the theory behind them. Finally, it details polymer and materials chemistry including such topics as conjugated block copolymers, metal-containing conjugated polymers, and continuous flow processing. Aimed at researchers, advanced students, and industry professionals working in materials science and engineering, this book covers fundamentals, recent progress, and new materials involved in conducting polymers and includes a wide-ranging listing of comprehensive chapters authored by an international team of experts.

Download or read book Scanning Probe Microscopy written by Vijay Nalladega and published by BoD – Books on Demand. This book was released on 2012-04-27 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scanning probe microscopy (SPM) is one of the key enabling tools for the advancement for nanotechnology with applications in many interdisciplinary research areas. This book presents selected original research works on the application of scanning probe microscopy techniques for the characterization of physical properties of different materials at the nanoscale. The topics in the book range from surface morphology analysis of thin film structures, oxide thin layers and superconducting structures, novel scanning probe microscopy techniques for characterization of mechanical and electrical properties, evaluation of mechanical and tribological properties of hybrid coatings and thin films. The variety of topics chosen for the book underlines the strong interdisciplinary nature of the research work in the field of scanning probe microscopy.

Download or read book Electrical Optical and Magnetic Properties of Organic Solid state Materials V written by Susan Ermer and published by . This book was released on 2000 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume, the fifth in a popular series, features papers related to the development and utilization of materials with novel electrical, optical or magnetic properties. The field has experienced tremendous growth in the past years, and this volume provides a forum for materials scientists, chemists, physicists and engineers to assess the progress. In particular, light-emitting materials for displays are showing great promise for widespread commercialization. Developments in molecular engineering and self assembly, as well as in conducting polymers, are enabling better performance and greater scientific understanding of the phenomena underlying these advances. Improvements in electro-optic, photorefractive and two-photon absorbing materials are also being realized and are addressed here.

Download or read book Lasers in Polymer Science and Technology written by Jan F. Rabek and published by CRC Press. This book was released on 1989-11-30 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this 4-volume set is to examine some of the applications of lasers in polymer science and technology. Now available for the first time, up-to-date information on this fascinating subject is compiled and presented in compact form. This set focuses on current research and developments in the application of lasers in polymer and biopolymer chemistry. It includes experimental and theoretical details, apparatus, techniques, and applications. This set is a useful source for researchers, students, polymer chemists, and physicists involved in this astonishing field of high technology.

Download or read book Handbook of Conducting Polymers 2 Volume Set written by Terje A. Skotheim and published by CRC Press. This book was released on 2007-01-16 with total page 1692 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn how recent advances are fueling new possibilities in textiles, optics, electronics, and biomedicine! As the field of conjugated, electrically conducting, and electroactive polymers has grown, the Handbook of Conducting Polymers has been there to document and celebrate these changes along the way. Now split into two vo

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2007 with total page 924 pages. Available in PDF, EPUB and Kindle. Book excerpt: