Download or read book Electronic Structure of Conjugated Materials and Their Effect on Organic Photovoltaics written by Chuanfei Wang and published by Linköping University Electronic Press. This book was released on 2017-11-15 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: The great tunability of structure and electronic properties of ?-conjugated organic molecules/polymers combined with other advantages such as light weight and flexibility etc., have made organic-based electronics the focus of an exciting still-growing field of physics and chemistry for more than half a century. The application of organic electronics has led to the appearance of wide range of organic electronic devices mainly including organic light emitting diodes (OLED), organic field effect transistors (OFET) and organic solar cells (OSC). The application of the organic electronic devices mainly is limited by two dominant parameters, i.e., their performance and stability. Up to date, OLED has been successfully commercialized in the market while the OSC are still on the way to commercialization hindered by low efficiency and inferior stability. Understanding the energy levels of organic materials and energy level alignment of the devices is crucial to control the efficiency and stability of the OSC. In this thesis, energy levels measured by different methods are studied to explore their relationship with device properties, and the strategies on how to design efficient and stable OSC based on energy level diagrams are provided. Cyclic Voltammetry (CV) is a traditional and widely used method to probe the energy levels of organic materials, although there is little consensus on how to relate the oxidation/reduction potential ((Eox/Ered) to the vacuum level. Ultraviolet Photoelectron Spectroscopy (UPS) can be used to directly detect vertical ionization potential (IP) of organic materials. In this thesis, a linear relationship of IP and Eox was found, with a slope equal to unity. The relationship provides for easy conversion of values obtained by the two techniques, enabling complementarily use in designing and fabricating efficient and stable OSC. A popular rule of thumb is that the offset between the LUMO levels of donor and acceptor should be 0.3 eV, according to which a binary solar cell with the minimum voltage losses around 0.49 V was designed here. Introduction of the ternary blend as active layer is an efficient way to improve both efficiency and stability of the OSC. Based on our studied energy-level diagram within the integer charge transfer (ICT) model, we designed ternary solar cells with enhanced open circuit voltage for the first time and improved thermal stability compared to reference binary ones. The ternary solar cell with minimum voltage losses was developed by combining two donor materials with same ionization potential and positive ICT energy while featuring complementary optical absorption. Furthermore, the fullerene acceptor was chosen so that the energy of the positive ICT state of the two donor polymers is equal to the energy of negative ICT state of the fullerene, which can enhance dissociation of all polymer donor and fullerene acceptor excitons and suppress bimolecular and trap-assistant recombination. Rapid development of non-fullerene acceptors in the last two years affords more recipes of designing both efficient and stabile OSC. We show in this thesis how non-fullerene acceptors successfully can be used to design ternary solar cells with both enhanced efficiency and thermal stability. Besides improving the efficiency of the devices, understanding of the stability and degradation mechanism is another key issue. The degradation of conjugated molecules/polymers often follow many complicated pathways and at the same time many factors for degradation are coupled with each other. Therefore, the degradation of non-fullerene acceptors was investigated in darkness by photoelectron spectroscopy in this thesis with the in-situ method of controlling exposure of O2 and water vapor separately.

Download or read book Wspc Reference On Organic Electronics The Organic Semiconductors In 2 Volumes written by Seth R Marder and published by World Scientific. This book was released on 2016-06-24 with total page 896 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 2-volume set provides the reader with a basic understanding of the foundational concepts pertaining to the design, synthesis, and applications of conjugated organic materials used as organic semiconductors, in areas including organic photovoltaic devices, light-emitting diodes, field-effect transistors, spintronics, actuation, bioelectronics, thermoelectrics, and nonlinear optics.While there are many monographs in these various areas, the emphasis here is both on the fundamental chemistry and physics concepts underlying the field of organic semiconductors and on how these concepts drive a broad range of applications. This makes the volumes ideal introductory textbooks in the subject. They will thus offer great value to both junior and senior scientists working in areas ranging from organic chemistry to condensed matter physics and materials science and engineering.Number of Illustrations and Tables: 168 b/w illus., 242 colour illus., 13 tables.

Download or read book Structure Function Relationships in Semiconducting Polymers for Organic Photovoltaics written by David Fredric Joel Kavulak and published by . This book was released on 2010 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: The major body of this work investigates how the chemical structure of conjugated polymers relates to the fundamental operating mechanism of organic photovoltaic devices. New conjugated polymers were characterized and their optical and electronic properties tested and correlated with their power conversion efficiencies as the active layer in polymer solar cells. From these experiments general structure/function relationships are drawn with an eye toward developing universal guidelines for conjugated polymer design and synthesis. Starting with light absorption, three major steps in the photovoltaic mechanism are examined. First, photogeneration of excited states and the migration of these states through the active layer are correlated to the polymeric backbone chemistry and the resulting device performance. Next, separation of these excited states at an interface between electron donors and electron acceptors is examined as a function of donor-acceptor distance and active layer dielectric constant. These two variables were tuned by chemical modification of polythiophene side groups. Third, charge carrier conduction is related to both polymer electronic states and to solid-state packing morphology. Design principles for effective conduction of both holes and electrons are outlined and the ambipolar nature of conjugated organic materials is discussed. In the final chapters, the solid-state polymer morphology in a solution processed thin film is examined. The impact that this morphology has on all steps in the photovoltaic mechanism is highlighted. How chemical modification of the polymer can influence this packing structure is examined as well as how new fabrication procedures can be used to pre-form nanostructured materials in solution before thin film deposition.

Download or read book A Study on Structure property Relationships of P3HT based Conjugated Polymers for Photovoltaic Devices written by Bobak Gholamkhass and published by . This book was released on 2011 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this research is to investigate structure-property relationships of a series of graft copolymers synthesized using a post-functionalization methodology in which non--conjugated segments are grafted onto a -conjugated polymer, poly(3-hexylthiophene). Taking advantage of the synthetic methodology, electron-acceptor molecules of fullerene are covalently attached to azide-functionalized graft chains grown from the polymer backbone. The goal is to gain knowledge regarding how to control the development of nanostructure morphology in binary blends of photoactive materials used in thin film solar devices. The study was initiated in the context of an increasing interest in nanostructure-molecular assemblies for organic photovoltaics. Post-functionalized poly(3-hexylthiophene) and fullerene (C_60) were employed as the primary materials in the study. Poly(3-hexylthiophene), a benchmark material for organic electronics, is selected as the structure of choice for testing hypotheses, which includes measures to stablilize the morphology of the bulk heterojunction thin films and improve the durability of organic solar cells. In this thesis research, the synthetic approach to obtain a series of donor-acceptor graft copolymers is explored with an emphasis on controlling structural parameters such as graft chain density, length and nature of the functional groups for attaching the fullerene moieties. The research involved detailed synthetic, characterization and morphological studies of these donor- and acceptor-type materials used for solar devices. The individual effects of the several structural parameters that could influence the property systematically investigated. The research outcome demonstrates that performance of a bulk heterojunction solar device is very sensitive to the morphology of the photoactive layer. Specifically, a stable morphology was achieved through a solid state, thermal reaction that initiated covalent attachment of the azide-functionalized graft chains to fullerene, "locking-in" the preformed domains. By purposely locking in the nanostructure, it was shown that stabilization of the morphology enhanced the stability of the solar devices. In addition, a novel device architecture that took advantage of a robust photoactive layer/metallic interface was proposed. The new device architecture in combination with morphology stabilization led to substanial improvements in performance stability. Novel polymeric structures, synthetic advancements and device architecture were the highlights of this research allowing a true study of durability of organic photovoltaic devices.

Download or read book Electronic Structure of Organic Semiconductors written by Luís Alcácer and published by Morgan & Claypool Publishers. This book was released on 2018-12-07 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written in the perspective of an experimental chemist, this book puts together some fundamentals from chemistry, solid state physics and quantum chemistry, to help with understanding and predicting the electronic and optical properties of organic semiconductors, both polymers and small molecules. The text is intended to assist graduate students and researchers in the field of organic electronics to use theory to design more efficient materials for organic electronic devices such as organic solar cells, light emitting diodes and field effect transistors. After addressing some basic topics in solid state physics, a comprehensive introduction to molecular orbitals and band theory leads to a description of computational methods based on Hartree-Fock and density functional theory (DFT), for predicting geometry conformations, frontier levels and energy band structures. Topological defects and transport and optical properties are then addressed, and one of the most commonly used transparent conducting polymers, PEDOT:PSS, is described in some detail as a case study.

Download or read book Polymer Photovoltaics written by Fei Huang and published by Royal Society of Chemistry. This book was released on 2016 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: An international perspective on the latest research in polymer solar cell technology.

Download or read book The Development of Semiconducting Materials for Organic Photovoltaics written by Jessica D. Douglas and published by . This book was released on 2013 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The chemical structure of conjugated semiconducting materials strongly influences the performance of organic photovoltaic (OPV) devices. Thus a good understanding of the structure-function relationships that govern the optoelectronic and physical properties of OPV materials is necessary. In this dissertation, organic polymers and small molecules are evaluated in terms of OPV device output parameters, and molecular design rules are elucidated. The development of molecules with alternating electron-rich and electron-deficient backbone units provides materials with suitable optoelectronic properties for OPVs and favorable modularity for organic semiconductor design. The choice of specific aromatic units and side chains for conjugated materials are shown to modulate the energy levels and architecture of OPV devices, affecting each of the four mechanistic steps of OPV operation. In Chapter 2, the relationship between molecular packing parameters and the bulkiness of aliphatic solubilizing group extending away from a polymer backbone is elucidated, and high-performance OPV devices are achieved. In Chapter 3, the inclusion of a post-processing functionality on a polymer side chain is found to have a positive effect on the bulk morphology and overall performance of OPV devices. In Chapter 4, the influence of electron-withdrawing and quinoidal monomers on the optoelectronic properties of conjugated polymers is established, and energy level modulation is shown to affect the electron accepting and donating capabilities of OPV materials in a blended device. In Chapter 5, small molecules are designed with complementary light absorption properties in order to investigate a rarely observed charge generation mechanism.

Download or read book Organic Photovoltaics written by Christoph Brabec and published by John Wiley & Sons. This book was released on 2011-09-22 with total page 597 pages. Available in PDF, EPUB and Kindle. Book excerpt: Providing complementary viewpoints from academia as well as technology companies, this book covers the three most important aspects of successful device design: materials, device physics, and manufacturing technologies. It also offers an insight into commercialization concerns, such as packaging technologies, system integration, reel-to-reel large scale manufacturing issues and production costs. With an introduction by Nobel Laureate Alan Heeger.

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.

Download or read book Organic Electronic Materials written by R. Farchioni and published by Springer Science & Business Media. This book was released on 2013-11-21 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book brings together selected contributions both on the fundamental information on the physics and chemistry of these materials, new physical ideas and decisive experiments. It constitutes both an insightful treatise and a handy reference for specialists and graduate students working in solid state physics and chemistry, material science and related fields.

Download or read book Organic Photovoltaics written by Sam-Shajing Sun and published by CRC Press. This book was released on 2017-12-19 with total page 916 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently developed organic photovoltaics (OPVs) show distinct advantages over their inorganic counterparts due to their lighter weight, flexible shape, versatile materials synthesis and device fabrication schemes, and low cost in large-scale industrial production. Although many books currently exist on general concepts of PV and inorganic PV materials and devices, few are available that offer a comprehensive overview of recently fast developing organic and polymeric PV materials and devices. Organic Photovoltaics: Mechanisms, Materials, and Devices fills this gap. The book provides an international perspective on the latest research in this rapidly expanding field with contributions from top experts around the world. It presents a unified approach comprising three sections: General Overviews; Mechanisms and Modeling; and Materials and Devices. Discussions include sunlight capture, exciton diffusion and dissociation, interface properties, charge recombination and migration, and a variety of currently developing OPV materials/devices. The book also includes two forewords: one by Nobel Laureate Dr. Alan J. Heeger, and the other by Drs. Aloysius Hepp and Sheila Bailey of NASA Glenn Research Center. Organic Photovoltaics equips students, researchers, and engineers with knowledge of the mechanisms, materials, devices, and applications of OPVs necessary to develop cheaper, lighter, and cleaner renewable energy throughout the coming decades.

Download or read book The Non Local Density of States of Electronic Excitations in Organic Semiconductors written by Carl. R Poelking and published by Springer. This book was released on 2017-10-24 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the microscopic understanding of the function of organic semiconductors. By tracing the link between their morphological structure and electronic properties across multiple scales, it represents an important advance in this direction. Organic semiconductors are materials at the interface between hard and soft matter: they combine structural variability, processibility and mechanical flexibility with the ability to efficiently transport charge and energy. This unique set of properties makes them a promising class of materials for electronic devices, including organic solar cells and light-emitting diodes. Understanding their function at the microscopic scale – the goal of this work – is a prerequisite for the rational design and optimization of the underlying materials. Based on new multiscale simulation protocols, the book studies the complex interplay between molecular architecture, supramolecular organization and electronic structure in order to reveal why some materials perform well – and why others do not. In particular, by examining the long-range effects that interrelate microscopic states and mesoscopic structure in these materials, the book provides qualitative and quantitative insights into e.g. the charge-generation process, which also serve as a basis for new optimization strategies.

Download or read book Handbook of Organic Materials for Electronic and Photonic Devices written by Oksana Ostroverkhova and published by Woodhead Publishing. This book was released on 2018-11-30 with total page 914 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Organic Materials for Electronic and Photonic Devices, Second Edition, provides an overview of the materials, mechanisms, characterization techniques, structure-property relationships, and most promising applications of organic materials. This new release includes new content on emerging organic materials, expanded content on the basic physics behind electronic properties, and new chapters on organic photonics. As advances in organic materials design, fabrication, and processing that enabled charge unprecedented carrier mobilities and power conversion efficiencies have made dramatic advances since the first edition, this latest release presents a necessary understanding of the underlying physics that enabled novel material design and improved organic device design. - Provides a comprehensive overview of the materials, mechanisms, characterization techniques, and structure property relationships of organic electronic and photonic materials - Reviews key applications, including organic solar cells, light-emitting diodes electrochemical cells, sensors, transistors, bioelectronics, and memory devices - New content to reflect latest advances in our understanding of underlying physics to enable material design and device fabrication

Download or read book Organic Solar Cells written by Barry P. Rand and published by CRC Press. This book was released on 2014-08-26 with total page 812 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic photovoltaic (OPV) cells have the potential to make a significant contribution to the increasing energy needs of the future. In this book, 15 chapters written by selected experts explore the required characteristics of components present in an OPV device, such as transparent electrodes, electron- and hole-conducting layers, as well as electron donor and acceptor materials. Design, preparation, and evaluation of these materials targeting highest performance are discussed. This includes contributions on modeling down to the molecular level to device-level electrical and optical testing and modeling, as well as layer morphology control and characterization. The integration of the different components in device architectures suitable for mass production is described. Finally, the technical feasibility and economic viability of large-scale manufacturing using fast inexpensive roll-to-roll deposition technologies is assessed.

Download or read book Solution Processable Components for Organic Electronic Devices written by Beata Luszczynska and published by John Wiley & Sons. This book was released on 2019-06-11 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides first-hand insights into advanced fabrication techniques for solution processable organic electronics materials and devices The field of printable organic electronics has emerged as a technology which plays a major role in materials science research and development. Printable organic electronics soon compete with, and for specific applications can even outpace, conventional semiconductor devices in terms of performance, cost, and versatility. Printing techniques allow for large-scale fabrication of organic electronic components and functional devices for use as wearable electronics, health-care sensors, Internet of Things, monitoring of environment pollution and many others, yet-to-be-conceived applications. The first part of Solution-Processable Components for Organic Electronic Devices covers the synthesis of: soluble conjugated polymers; solution-processable nanoparticles of inorganic semiconductors; high-k nanoparticles by means of controlled radical polymerization; advanced blending techniques yielding novel materials with extraordinary properties. The book also discusses photogeneration of charge carriers in nanostructured bulk heterojunctions and charge carrier transport in multicomponent materials such as composites and nanocomposites as well as photovoltaic devices modelling. The second part of the book is devoted to organic electronic devices, such as field effect transistors, light emitting diodes, photovoltaics, photodiodes and electronic memory devices which can be produced by solution-based methods, including printing and roll-to-roll manufacturing. The book provides in-depth knowledge for experienced researchers and for those entering the field. It comprises 12 chapters focused on: ? novel organic electronics components synthesis and solution-based processing techniques ? advanced analysis of mechanisms governing charge carrier generation and transport in organic semiconductors and devices ? fabrication techniques and characterization methods of organic electronic devices Providing coverage of the state of the art of organic electronics, Solution-Processable Components for Organic Electronic Devices is an excellent book for materials scientists, applied physicists, engineering scientists, and those working in the electronics industry.

Download or read book Organic Photovoltaics written by Christoph Joseph Brabec and published by Springer Science & Business Media. This book was released on 2013-11-21 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present volume describes and explains the fundamentals of organic/plastic solar cells in a manner accessible to both researchers and students. It provides an up-to-date and comprehensive account of these materials and corresponding devices, which will play a key role in future solar energy systems.

Download or read book Organic Solar Cells written by Wallace C.H. Choy and published by Springer Science & Business Media. This book was released on 2012-11-19 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic solar cells have emerged as new promising photovoltaic devices due to their potential applications in large area, printable and flexible solar panels. Organic Solar Cells: Materials and Device Physics offers an updated review on the topics covering the synthesis, properties and applications of new materials for various critical roles in devices from electrodes, interface and carrier transport materials, to the active layer composed of donors and acceptors. Addressing the important device physics issues of carrier and exciton dynamics and interface stability and novel light trapping structures, the potential for hybrid organic solar cells to provide high efficiency solar cells is examined and discussed in detail. Specific chapters covers key areas including: Latest research and designs for highly effective polymer donors/acceptors and interface materials Synthesis and application of highly transparent and conductive graphene Exciton and charge dynamics for in-depth understanding of the mechanism underlying organic solar cells. New potentials and emerging functionalities of plasmonic effects in OSCs Interface Degradation Mechanisms in organic photovoltaics improving the entire device lifetime Device architecture and operation mechanism of organic/ inorganic hybrid solar cells for next generation of high performance photovoltaics This reference can be practically and theoretically applied by senior undergraduates, postgraduates, engineers, scientists, researchers, and project managers with some fundamental knowledge in organic and inorganic semiconductor materials or devices.