Download or read book Excitonic States and Optoelectronic Properties of Organic Semiconductors written by Christof Walter and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Excitonic State and Optoelectronic Properties of Organic Semiconductors written by Christof Walter and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Optoelectronic Properties of Organic Semiconductors written by Nasim Zarrabi and published by Springer Nature. This book was released on 2022-02-26 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on organic semiconductors with particular attention paid to their use as photovoltaic devices. It addresses a fundamental and hitherto overlooked concept in the field of organic optoelectronics, namely the role that sub-gap states play in the performance of organic semiconducting devices. From a technological point of view, organic semiconductor-based devices are of significant interest due to their lightweight, ease of processability, conformal flexibility, and potentially low cost and low embodied energy production. Motivated by these rather unique selling points, the performance of organic semiconductors has been a subject of multidisciplinary study for more than 60 years with steady progress in applications such as solar cells, transistors, light emitting diodes, and various sensors. The book begins with a review of the main electro-optical phenomena in organic solar cells and presents a new method for measuring exciton diffusion lengths based on a low-quencher-content device structure. Furthermore, the book reveals how mid-gap trap states are a universal feature in organic semiconductor donor–acceptor blends, unexpectedly contributing to charge generation and recombination, and having profound impact on the thermodynamic limit of organic photovoltaic devices. Featuring cutting-edge experimental observations supported with robust and novel theoretical arguments, this book delivers important new insight as to the underlying dynamics of exciton generation and diffusion, charge transfer state dissociation, and indeed the ultimate fate of photogenerated free carriers.

Download or read book Optoelectronic Properties of Organic Semiconductors written by Nasim Zarrabi and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on organic semiconductors with particular attention paid to their use as photovoltaic devices. It addresses a fundamental and hitherto overlooked concept in the field of organic optoelectronics, namely the role that sub-gap states play in the performance of organic semiconducting devices. From a technological point of view, organic semiconductor-based devices are of significant interest due to their lightweight, ease of processability, conformal flexibility, and potentially low cost and low embodied energy production. Motivated by these rather unique selling points, the performance of organic semiconductors has been a subject of multidisciplinary study for more than 60 years with steady progress in applications such as solar cells, transistors, light emitting diodes, and various sensors. The book begins with a review of the main electro-optical phenomena in organic solar cells and presents a new method for measuring exciton diffusion lengths based on a low-quencher-content device structure. Furthermore, the book reveals how mid-gap trap states are a universal feature in organic semiconductor donor-acceptor blends, unexpectedly contributing to charge generation and recombination, and having profound impact on the thermodynamic limit of organic photovoltaic devices. Featuring cutting-edge experimental observations supported with robust and novel theoretical arguments, this book delivers important new insight as to the underlying dynamics of exciton generation and diffusion, charge transfer state dissociation, and indeed the ultimate fate of photogenerated free carriers.

Download or read book On Exciton Vibration and Exciton Photon Interactions in Organic Semiconductors written by Antonios M. Alvertis and published by Springer Nature. This book was released on 2021-10-25 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: What are the physical mechanisms that underlie the efficient generation and transfer of energy at the nanoscale? Nature seems to know the answer to this question, having optimised the process of photosynthesis in plants over millions of years of evolution. It is conceivable that humans could mimic this process using synthetic materials, and organic semiconductors have attracted a lot of attention in this respect. Once an organic semiconductor absorbs light, bound pairs of electrons with positively charged holes, termed `excitons’, are formed. Excitons behave as fundamental energy carriers, hence understanding the physics behind their efficient generation and transfer is critical to realising the potential of organic semiconductors for light-harvesting and other applications, such as LEDs and transistors. However, this problem is extremely challenging since excitons can interact very strongly with photons. Moreover, simultaneously with the exciton motion, organic molecules can vibrate in hundreds of possible ways, having a very strong effect on energy transfer. The description of these complex phenomena is often beyond the reach of standard quantum mechanical methods which rely on the assumption of weak interactions between excitons, photons and vibrations. In this thesis, Antonios Alvertis addresses this problem through the development and application of a variety of different theoretical methods to the description of these strong interactions, providing pedagogical explanations of the underlying physics. A comprehensive introduction to organic semiconductors is followed by a review of the background theory that is employed to approach the relevant research questions, and the theoretical results are presented in close connection with experiment, yielding valuable insights for experimentalists and theoreticians alike.

Download or read book Synthetic Control of Organic Semiconductor Excited States written by Tabitha Ann Clem and published by . This book was released on 2010 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work describes the synthesis, and study of new organic and organometallic compounds designed to possess modified excited states for applications in electronic devices, with a particular focus on photovoltaics. The first chapter introduces the origin of semiconducting behavior in conjugated polymers, and how the properties of these semiconductors ultimately impact the fundamental physical processes occurring in organic electronic devices. The second chapter describes the synthesis, optoelectronic properties, and photovoltaic performance of a small molecule oligothiophene analog that possesses a considerable redshift in absorption relative to an unmodified oligothiophene. This redshift in absorption is the result of using a fused thiophene unit that acts as a driving force to enable dearomatization of the oligothiophene unit. The third chapter describes the preparation of wide band gap, phosphorescent cyclometalated platinum polymers and their application to bilayer photovoltaic devices where an increase in photocurrent is observed, and is attributed to an increase in the exciton diffusion length arising from formation of triplet excitons. The fourth chapter presents further development of cyclometalated platinum polymers, with a focus on tuning the photophysical properties and studying these materials in bulk heterojunction photovoltaic devices. The fifth chapter presents a study of cyclometalated platinum and iridium small molecules, describing their photophysical properties and solid-state structure, and exploring the application of these complexes to light emitting diodes. The final chapter describes the development of polythiophenes containing highly polarizable functional groups, with particular attention to the effect of these modifications on the optoelectronic properties and the dielectric constants of the resulting polymers. Together, these chapters present a study encompassing the modification of excited states in organic semiconductors, beginning with light absorption, continuing to modification of the spin state of the exciton, and ultimately modifying the dielectric constant of the active layer materials to affect charge separation and transport. Utilizing materials developed based on these principles provides an attractive new route to altering and enhancing the basic steps involved in the operation of organic electronic devices, ultimately producing both an improved understanding of the mechanism of device operation, and improved device performance.

Download or read book Spectroscopy And Optoelectronics In Semiconductors And Related Materials Proceedings Of The Sino soviet Seminar written by Sue-chu Shen and published by World Scientific. This book was released on 1990-11-23 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume covers new results from recent studies on impurity states, bound states in semiconductors, phonons, excitons and electron confinement in superlattices and quantum wells, magnetooptics, optical properties of solids in far infrared and millimeter wave regions, optical nonlinearity for III-V, II-VI compounds, Si, Ge, amorphous and organic semiconductors as well as optical crystals. Special emphasis is placed on the 2DEG system.

Download or read book Excitonic and Photonic Processes in Materials written by Jai Singh and published by Springer. This book was released on 2014-07-29 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is expected to present state-of-the-art understanding of a selection of excitonic and photonic processes in useful materials from semiconductors to insulators to metal/insulator nanocomposites, both inorganic and organic. Among the featured applications are components of solar cells, detectors, light-emitting devices, scintillators and materials with novel optical properties. Excitonic properties are particularly important in organic photovoltaics and light emitting devices, as also in questions of the ultimate resolution and efficiency of new-generation scintillators for medical diagnostics, border security and nuclear non proliferation. Novel photonic and optoelectronic applications benefit from new material combinations and structures to be discussed.

Download or read book Electronic and Optoelectronic Properties of Semiconductor Structures written by Jasprit Singh and published by Cambridge University Press. This book was released on 2007-03-26 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: A graduate textbook presenting the underlying physics behind devices that drive today's technologies. The book covers important details of structural properties, bandstructure, transport, optical and magnetic properties of semiconductor structures. Effects of low-dimensional physics and strain - two important driving forces in modern device technology - are also discussed. In addition to conventional semiconductor physics the book discusses self-assembled structures, mesoscopic structures and the developing field of spintronics. The book utilizes carefully chosen solved examples to convey important concepts and has over 250 figures and 200 homework exercises. Real-world applications are highlighted throughout the book, stressing the links between physical principles and actual devices. Electronic and Optoelectronic Properties of Semiconductor Structures provides engineering and physics students and practitioners with complete and coherent coverage of key modern semiconductor concepts. A solutions manual and set of viewgraphs for use in lectures are available for instructors, from [email protected].

Download or read book Charge Transfer and Strongly Coupled States in Organic Photovoltaics written by Alyssa Nicole Brigeman and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic semiconductors have attracted widespread interest over the past few decades due to their relative ease of processing, ability to be deposited on low-cost and flexible substrates, and the prospect of limitless tunability of their electrical and optical properties. A fundamental feature of organic semiconductors is the excitonic nature of molecular excited states supported by the weakly-bound, low dielectric constant solids, which makes organics scientifically interesting yet challenging with respect to incorporation into marketable optoelectronic devices. The first component of this thesis focuses on the implications of excitons on practical organic semiconductor devices, particularly organic photovoltaics (OPVs) and the complicated process of free charge generation enforced by excitons. The second part of this work concerns an investigation of how excitons respond to strong light-matter coupling in organic semiconductor microcavities, which has proven to be interesting for applications in organic optoelectronic devices including OPVs, organic light-emitting diodes (OLEDs) and lasers.OPVs currently lag behind their inorganic counterparts in overall performance, due in part to energy losses stemming from the excitonic nature of organic semiconductors which has inhibited widespread commercial viability. In order to overcome the current set of challenges associated with OPVs, a better understanding of the charge generation process and associated loss mechanisms is critical. Unlike inorganic semiconductors which directly generate free electrons and holes upon absorption of a photon, a photoabsorption event in an OPV device instead produces a tightly-bound electron-hole pair, called an exciton, which requires energetic assistance from interfacial charge transfer (CT) states to dissociate. Despite wide recognition of the importance of CT states to charge generation, recombination losses, and open-circuit voltage, characterization of these states is lacking due to stronger overlapping excitonic features in absorption and emission by composite molecules. A method to extract CT state absorption from the overlapping excitonic background by exploiting the natural alignment of CT states at a planar donor/acceptor (DA) heterojunction via polarized external quantum efficiency (EQE) measurements was developed in this thesis, which allows for an accurate calculation of critical OPV parameters such as CT state energy, reorganization energy, and energetic disorder-induced broadening. The polarized EQE analysis introduced in this work offers a technique to more comprehensively the understand nature and role of CT states and rigorously determine CT state parameters that directly affect the power conversion efficiency of OPVs.Another fundamental unknown regarding operational OPVs concerns the CT density of states (DOS) at the DA interface and its occupation under illumination. The CT DOS carries important implications that affect the performance of OPVs, such as added voltage losses and the potential for barrier-less charge separation, yet surprisingly little is known about its functional form, how carriers relax within it, and how the CT DOS relates to the joint density of free electron and hole states. By sensitively measuring weak emission from CT states in small molecule OPV systems in time with picosecond resolution, as a function of temperature down to 100 K, and with applied bias, the most complete picture to date of the CT DOS occupation and relaxation was realized in this thesis. Better understanding the relaxation processes that contribute to voltage losses is the first step towards engineering OPV devices with maximum power conversion efficiencies.The last part of this work investigates strong exciton-photon coupling in OPV-inspired microcavity devices resulting in exciton-polaritons. Polaritons are a result of the interaction between electronic excitations in a material (typically excitons) and the photon mode associated with a microcavity. Strong coupling of the exciton and photon occurs when the light-matter interaction far exceeds cavity damping or exciton dephasing, and is relatively easily observed from organic semiconductor microcavities due to the stability of excitons at room temperature in molecular solids. Ultrastrong coupling, a regime in which the interaction energy is a significant fraction of the bare exciton energy, is achieved from planar and bulk heterojunction devices. A thorough study of emission from the ultrastrongly-coupled cavities provides insight into the population of polariton states.

Download or read book Optoelectronic Organic Inorganic Semiconductor Heterojunctions written by Ye Zhou and published by CRC Press. This book was released on 2021-01-19 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optoelectronic Organic-Inorganic Semiconductor Heterojunctions summarizes advances in the development of organic-inorganic semiconductor heterojunctions, points out challenges and possible solutions for material/device design, and evaluates prospects for commercial applications. Introduces the concept and basic mechanism of semiconductor heterojunctions Describes a series of organic-inorganic semiconductor heterojunctions with desirable electrical and optical properties for optoelectronic devices Discusses typical devices such as solar cells, photo-detectors, and optoelectronic memories Outlines the materials and device challenges as well as possible strategies to promote the commercial translation of semiconductor heterojunctions-based optoelectronic devices Aimed at graduate students and researchers working in solid-state materials and electronics, this book offers a comprehensive yet accessible view of the state of the art and future directions.

Download or read book Introduction to Organic Electronic and Optoelectronic Materials and Devices written by Sam-Shajing Sun and published by CRC Press. This book was released on 2008-05-29 with total page 936 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reflecting rapid growth in research and development on organic/polymeric electronic and photonic materials and devices, Introduction to Organic Electronic and Optoelectronic Materials and Devices provides comprehensive coverage of the state-of-the-art in an accessible format. The book presents fundamentals, principles, and mechanisms complem

Download or read book Organic Optoelectronic Materials written by Yongfang Li and published by Springer. This book was released on 2015-05-30 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume reviews the latest trends in organic optoelectronic materials. Each comprehensive chapter allows graduate students and newcomers to the field to grasp the basics, whilst also ensuring that they have the most up-to-date overview of the latest research. Topics include: organic conductors and semiconductors; conducting polymers and conjugated polymer semiconductors, as well as their applications in organic field-effect-transistors; organic light-emitting diodes; and organic photovoltaics and transparent conducting electrodes. The molecular structures, synthesis methods, physicochemical and optoelectronic properties of the organic optoelectronic materials are also introduced and described in detail. The authors also elucidate the structures and working mechanisms of organic optoelectronic devices and outline fundamental scientific problems and future research directions. This volume is invaluable to all those interested in organic optoelectronic materials.

Download or read book World Scientific Handbook Of Organic Optoelectronic Devices Volumes 1 2 written by and published by World Scientific. This book was released on 2018-06-29 with total page 908 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic (opto)electronic materials have received considerable attention due to their applications in perovskite and flexible electronics, OPVs and OLEDs and many others. Reflecting the rapid growth in research and development of organic (opto)electronic materials over the last few decades, this book provides a comprehensive coverage of the state of the art in an accessible format. It presents the most widely recognized fundamentals, principles, and mechanisms along with representative examples, key experimental data, and over 200 illustrative figures.

Download or read book Exciton Dynamics in Lead Halide Perovskite Nanocrystals written by Bernhard Johann Bohn and published by Springer Nature. This book was released on 2021-05-18 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: Less than a decade ago, lead halide perovskite semiconductors caused a sensation: Solar cells exhibiting astonishingly high levels of efficiency. Recently, it became possible to synthesize nanocrystals of this material as well. Interestingly; simply by controlling the size and shape of these crystals, new aspects of this material literally came to light. These nanocrystals have proven to be interesting candidates for light emission. In this thesis, the recombination, dephasing and diffusion of excitons in perovskite nanocrystals is investigated using time-resolved spectroscopy. All these dynamic processes have a direct impact on the light-emitting device performance from a technology point of view. However, most importantly, the insights gained from the measurements allowed the author to modify the nanocrystals such that they emitted with an unprecedented quantum yield in the blue spectral range, resulting in the successful implementation of this material as the active layer in an LED. This represents a technological breakthrough, because efficient perovskite light emitters in this wavelength range did not exist before.

Download or read book Optoelectronic Properties of Inorganic Compounds written by D. Max Roundhill and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is intended to offer the reader a snapshot of the field of optoelectronic materials from the viewpoint of inorganic chemists. The field of inorganic chemistry is transforming from one focused on the synthesis of compounds having interesting coordination numbers, structures, and stereochemistries, to one focused on preparing compounds that have potentially useful practical applica tions. Two such applications are in the area of optics and electronics. These are fields where the use of inorganic materials has a long history. As the field of microelectronics develops the demands on the performance of such materials increases, and it becomes necessary to discover compounds that will meet these demands. The field of optoelectronics represents a merging of the two disciplines. Its emergence is a natural one because many of the applications involve both of these properties, and also because the electronic structure of a metal compound that confers novel optical properties is often one that also influences its electron transfer and conductivity characteristics. Two of the more important growth areas that have led to these developments are communications and medicine. Within the communications field there is the microelectronics that is involved in information storage and transmittal, some of which will be transferred into the optical regime. Within the medical field there are chemical probes that transmit analytical information from an in vivo environment. This information needs to be readily accessible from an external site, and then quickly converted into images or data that yield accurate and inexpensive diagnoses.

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.