Download or read book Doping and Density of States Engineering for Organic Thermoelectrics written by Guangzheng Zuo and published by Linköping University Electronic Press. This book was released on 2018-05-14 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermoelectric materials can turn temperature differences directly into electricity. To use this to harvest e.g. waste heat with an efficiency that approaches the Carnot efficiency requires a figure of merit ZT larger than 1. Compared with their inorganic counterparts, organic thermoelectrics (OTE) have numerous advantages, such as low cost, large-area compatibility, flexibility, material abundance and an inherently low thermal conductivity. Therefore, organic thermoelectrics are considered by many to be a promising candidate material system to be used in lower cost and higher efficiency thermoelectric energy conversion, despite record ZT values for OTE currently lying around 0.25. A complete organic thermoelectric generator (TEG) normally needs both p-type and n-type materials to form its electric circuit. Molecular doping is an effective way to achieve p- and ntype materials using different dopants, and it is necessary to fundamentally understand the doping mechanism. We developed a simple yet quantitative analytical model and compare it with numerical kinetic Monte Carlo simulations to reveal the nature of the doping effect. The results show the formation of a deep tail in the Gaussian density of states (DOS) resulting from the Coulomb potentials of ionized dopants. It is this deep trap tail that negatively influences the charge carrier mobility with increasing doping concentration. The trends in mobilities and conductivities observed from experiments are in good agreement with the modeling results, for a large range of materials and doping concentrations. Having a high power factor PF is necessary for efficient TEG. We demonstrate that the doping method can heavily impact the thermoelectric properties of OTE. In comparison to conventional bulk doping, sequential doping can achieve higher conductivity by preserving the morphology, such that the power factor can improve over 100 times. To achieve TEG with high output power, not only a high PF is needed, but also having a significant active layer thickness is very important. We demonstrate a simple way to fabricate multi-layer devices by sequential doping without significantly sacrificing PF. In addition to the application discussed above, harvesting large amounts of heat at maximum efficiency, organic thermoelectrics may also find use in low-power applications like autonomous sensors where voltage is more important than power. A large output voltage requires a high Seebeck coefficient. We demonstrate that density of states (DOS) engineering is an effective tool to increase the Seebeck coefficient by tailoring the positions of the Fermi energy and the transport energy in n- and p-type doped blends of conjugated polymers and small molecules. In general, morphology heavily impacts the performance of organic electronic devices based on mixtures of two (or more) materials, and organic thermoelectrics are no exception. We experimentally find that the charge and energy transport is distinctly different in well-mixed and phase separated morphologies, which we interpreted in terms of a variable range hopping model. The experimentally observed trends in conductivity and Seebeck coefficient are reproduced by kinetic Monte Carlo simulations in which the morphology is accounted for.

Download or read book Doping and Density of States Engineering for Organic Thermoelectrics written by Guangzheng Zuo and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermoelectric materials can turn temperature differences directly into electricity. To use this to harvest e.g. waste heat with an efficiency that approaches the Carnot efficiency requires a figure of merit ZT larger than 1. Compared with their inorganic counterparts, organic thermoelectrics (OTE) have numerous advantages, such as low cost, large-area compatibility, flexibility, material abundance and an inherently low thermal conductivity. Therefore, organic thermoelectrics are considered by many to be a promising candidate material system to be used in lower cost and higher efficiency thermoelectric energy conversion, despite record ZT values for OTE currently lying around 0.25. A complete organic thermoelectric generator (TEG) normally needs both p-type and n-type materials to form its electric circuit. Molecular doping is an effective way to achieve p- and ntype materials using different dopants, and it is necessary to fundamentally understand the doping mechanism. We developed a simple yet quantitative analytical model and compare it with numerical kinetic Monte Carlo simulations to reveal the nature of the doping effect. The results show the formation of a deep tail in the Gaussian density of states (DOS) resulting from the Coulomb potentials of ionized dopants. It is this deep trap tail that negatively influences the charge carrier mobility with increasing doping concentration. The trends in mobilities and conductivities observed from experiments are in good agreement with the modeling results, for a large range of materials and doping concentrations. Having a high power factor PF is necessary for efficient TEG. We demonstrate that the doping method can heavily impact the thermoelectric properties of OTE. In comparison to conventional bulk doping, sequential doping can achieve higher conductivity by preserving the morphology, such that the power factor can improve over 100 times. To achieve TEG with high output power, not only a high PF is needed, but also having a significant active layer thickness is very important. We demonstrate a simple way to fabricate multi-layer devices by sequential doping without significantly sacrificing PF. In addition to the application discussed above, harvesting large amounts of heat at maximum efficiency, organic thermoelectrics may also find use in low-power applications like autonomous sensors where voltage is more important than power. A large output voltage requires a high Seebeck coefficient. We demonstrate that density of states (DOS) engineering is an effective tool to increase the Seebeck coefficient by tailoring the positions of the Fermi energy and the transport energy in n- and p-type doped blends of conjugated polymers and small molecules. In general, morphology heavily impacts the performance of organic electronic devices based on mixtures of two (or more) materials, and organic thermoelectrics are no exception. We experimentally find that the charge and energy transport is distinctly different in well-mixed and phase separated morphologies, which we interpreted in terms of a variable range hopping model. The experimentally observed trends in conductivity and Seebeck coefficient are reproduced by kinetic Monte Carlo simulations in which the morphology is accounted for.

Download or read book Organic Thermoelectric Materials written by Zhiqun Lin and published by Royal Society of Chemistry. This book was released on 2019-10-18 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarises the significant progress made in organic thermoelectric materials, focusing on effective routes to minimize thermal conductivity and maximize power factor.

Download or read book Organic Thermoelectrics written by Daoben Zhu and published by John Wiley & Sons. This book was released on 2022-11-03 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic Thermoelectrics Enables readers to understand the development and applications of organic thermoelectric conversion, including fundamentals and experimental breakthroughs Organic Thermoelectrics: From Materials to Devices introduces organic thermoelectric materials to devices in a systematic manner, covering the development of organic thermoelectric materials, followed by a discussion on the fundamental mechanism of thermoelectric conversion, design strategy, and advances in different materials, device fabrication, and characterizations of thermoelectric parameters. In Organic Thermoelectrics: From Materials to Devices, readers can expect to find detailed information on: Fundamentals of thermoelectric (TE) conversion, development of organic thermoelectric (OTE) fields and mechanisms, and basic physical processes in carrier transport and thermal transport for TE conversion Recent development and key strategies to develop p-type, n-type, and composite/hybrid OTE materials Basic mechanisms, fundamental requirements, and recent advances of doping for OTE applications, plus geometries and construction methods of OTE devices Theoretical and experimental advances in single molecular TE devices, together with the recent development in related detection methods Powered by worldwide innovative research results in the past ten years and strongly supported by many collaborators, Organic Thermoelectrics is a comprehensive reference on the subject and is invaluable for scientists and students in chemistry, materials, and engineering.

Download or read book Innovative Thermoelectric Materials Polymer Nanostructure And Composite Thermoelectrics written by Howard E Katz and published by World Scientific. This book was released on 2016-01-22 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: Power generation from environmentally friendly sources has led to surging interest in thermoelectrics. There has been a move toward alternative thermoelectric materials with enhanced performance through materials and structures that utilize common and safer elements and alternative mechanistic approaches while increasing processing latitude and decreasing cost. This wide-ranging volume examines this progress and future prospects with the new technologies, ease of processing and cost as major considerations, and will benefit active researchers, students and others interested in cutting-edge work in thermoelectric materials. Innovative Thermoelectric Materials incorporates the contributions of a group of recognized experts in thermoelectric materials, many of whom were the first to introduce various materials systems into thermoelectric systems. The perspectives brought to this evolving subject will provide important insights on which those developing the field can build, and will inspire new research directions for the future.

Download or read book Thermoelectric Materials and Devices written by Iris Nandhakumar and published by Royal Society of Chemistry. This book was released on 2017 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt: Authoritative account of recent developments in thermoelectric materials and devices for power energy harvesting applications, ideal for researchers and industrialists in materials science.

Download or read book Bringing Thermoelectricity into Reality written by Patricia Aranguren and published by BoD – Books on Demand. This book was released on 2018-07-11 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: The disproportionate use of fossil fuels has turned into a serious environmental issue. Thus, we are encountering one of the biggest challenges of the twenty-first century, satisfying the energy demand with respect to the environment. Thermoelectricity is an emerging technology, which contributes to reducing the impact of the use of traditional technologies, harvesting the waste heat, and eliminating the use of refrigerants. The book Bringing Thermoelectricity into Reality covers the current thermoelectric investigations: the study of novel thermoelectric materials, the development of computational models, the design of proper assemblies, and the optimization of thermal designs, as well as novel thermoelectric generators, coolers, and heating applications. This book looks for the definitive thermoelectric applications applied to everyday life.

Download or read book Introduction to Thermoelectricity written by H. Julian Goldsmid and published by Springer Science & Business Media. This book was released on 2009-10-03 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to Thermoelectricity is the latest work by Professor Julian Goldsmid drawing on his 55 years experience in the field. The theory of the thermoelectric and related phenomena is presented in sufficient detail to enable researchers to understand their observations and develop improved thermoelectric materials. The methods for the selection of materials and their improvement are discussed. Thermoelectric materials for use in refrigeration and electrical generation are reviewed. Experimental techniques for the measurement of properties and for the production of thermoelements are described. Special emphasis is placed on nanotechnology which promises to yield great improvements in the efficiency of thermoelectric devices. Chapters are also devoted to transverse thermoelectric effects and thermionic energy conversion, both techniques offering the promise of important applications in the future.

Download or read book Molecular Doping of Organic Semiconductors written by Torben Menke and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Thermoelectric Energy Conversion written by Diana Davila Pineda and published by John Wiley & Sons. This book was released on 2017-09-12 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: The latest volume in the well-established AMN series, this ready reference provides an up-to-date, self-contained summary of recent developments in the technologies and systems for thermoelectricity. Following an initial chapter that introduces the fundamentals and principles of thermoelectricity, subsequent chapters discuss the synthesis and integration of various bulk thermoelectric as well as nanostructured materials. The book then goes on to discuss characterization techniques, including various light and mechanic microscopy techniques, while also summarizing applications for thermoelectric materials, such as micro- and nano-thermoelectric generators, wearable electronics and energy conversion devices. The result is a bridge between industry and scientific researchers seeking to develop thermoelectric generators.

Download or read book Advanced Thermoelectric Materials for Energy Harvesting Applications written by Saim Memon and published by BoD – Books on Demand. This book was released on 2019-10-30 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Thermoelectric Materials for Energy Harvesting Applications is a research-intensive textbook covering the fundamentals of thermoelectricity and the process of converting heat energy into electrical energy. It covers the design, implementation, and performance of existing and advanced thermoelectric materials. Chapters examine such topics as organic/inorganic thermoelectric materials, performance and behaviors of thermoelectric devices, and energy harvesting applications of thermoelectric devices.

Download or read book Polymers in Energy Conversion and Storage written by Inamuddin and published by CRC Press. This book was released on 2022-06-28 with total page 363 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research and development activities in energy conversion and storage are playing a significant role in our daily lives owing to the rising interest in clean energy technologies to alleviate the fossil-fuel crisis. Polymers are used in energy conversion and storage technology due to their low-cost, softness, ductility and flexibility compared to carbon and inorganic materials. Polymers in Energy Conversion and Storage provides in-depth literature on the applicability of polymers in energy conversion and storage, history and progress, fabrication techniques, and potential applications. Highly accomplished experts review current and potential applications including hydrogen production, solar cells, photovoltaics, water splitting, fuel cells, supercapacitors and batteries. Chapters address the history and progress, fabrication techniques, and many applications within a framework of basic studies, novel research, and energy applications. Additional Features Include: Explores all types of energy applications based on polymers and its composites Provides an introduction and essential concepts tailored for the industrial and research community Details historical developments in the use of polymers in energy applications Discusses the advantages of polymers as electrolytes in batteries and fuel cells This book is an invaluable guide for students, professors, scientists and R&D industrial experts working in the field.

Download or read book Thermoelectric Materials written by Enrique Macia and published by CRC Press. This book was released on 2015-05-05 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: Environmental and economic concerns have significantly spurred the search for novel, high-performance thermoelectric materials for energy conversion in small-scale power generation and refrigeration devices. This quest has been mainly fueled by the introduction of new designs and the synthesis of new materials. In fact, good thermoelectric material

Download or read book Doping of Carbon Nanotubes written by Sergey Bulyarskiy and published by Springer. This book was released on 2017-07-01 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the control of electronic properties of carbon nanotubes. It presents thermodynamic calculations of the formation of impurities and defects in the interaction of nanotubes with hydrogen, oxygen, nitrogen and boron, based on theoretical models of the formation of defects in carbon nanotubes. It is shown that doping and adsorption lead to changes in the electronic structure of the tubes as well as to the appearance of impurity states in the HOMO-LUMO gap. The book presents examples of specific calculations for doping of carbon nanotubes with oxygen, hydrogen, nitrogen and boron, together with numerous experimental results and a comparison with the author’s thermodynamic calculations. Possible directions of the technological processes of optimization are pointed out, as well as the perspectives of p-n-transition creation with the help of carbon nanotube arrays. The results presented were derived from the physics of the processes and a theoretical model of the technological processes. Though a wealth of empirical information on doping nanotubes has been accumulated in the scientific literature, what is lacking is a theoretical model for their analysis. As such, the book develops a thermodynamic model of the self-organization of structural elements in multicomponent systems – including carbon nanotubes, clusters and precipitates in condensed matter – and subsequently adapts it to the doping of carbon nanotubes. This approach allows readers to gain a far deeper understanding of the processes of doping carbon nanotubes.

Download or read book Flexible Thermoelectric Polymers and Systems written by Jianyong Ouyang and published by John Wiley & Sons. This book was released on 2022-01-20 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flexible Thermoelectric Polymers and Systems Comprehensive review of the rapidly evolving field of flexible thermoelectric polymers Flexible Thermoelectric Polymers and Systems delivers an expansive exploration of the most recent developments in flexible thermoelectric polymers and composites, as well as their applications in thermoelectric generators and Peltier coolers. The book focuses on novel designs and applications of technologies such as low-dimensional thermoelectric materials and how the latest advances have begun to overcome problems including poor mechanical flexibility and high fabrication costs. The book begins with a review of the fundamentals of thermoelectric materials, including discussions of the properties of thermoelectric materials, the Seebeck, Peltier, and Thomson effects, electrical conductivity, thermal conductivity, and thermoelectric generators, cooling, and sensors. It goes on to discuss more advanced developments in the field, such as flexible thermoelectric plastics and the thermoelectric properties of conducting polymers with ionic conductors. The book also includes: Thorough introductions to thermoelectric materials and systems, as well as the chemistry and physics of intrinsically conductive polymers Comprehensive explorations of thermoelectric PEDOTs, p-type thermoelectric polymers, and N-type thermoelectric polymers Practical discussions of thermoelectric composites of carbon nanotubes, graphene, and nanomaterials In-depth examinations of polymer composites of inorganic thermoelectric semiconductors Perfect for academic and industrial researchers and engineers in physics, materials science, chemistry, and engineering, Flexible Thermoelectric Polymers and Systems is also an indispensable resource for graduate students and early-career professionals working in those fields.

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 909 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

Download or read book Impact of Chemical Doping on the Thermoelectric Charge Transport of Organic Semiconductors written by Connor J. Boyle and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The thermoelectric properties of organic semiconductors allow them to directly convert heat into electricity without the use of moving parts and to directly convert electricity into heat without the use of working fluids. These properties offer opportunities for the generation of electricity from non-conventional or renewable sources of heat and for refrigeration without the risk of leaking harmful working fluids at any length scale down to the nanoscale. Since organic materials are lightweight, flexible, and made from abundant resources, these opportunities could one day become affordable for widespread use and could be expanded to include specialized and otherwise difficult to reach applications, such as wearable refrigeration and electricity generation from anthropogenic heat. Since these properties are a result of how charge carriers in organic materials transfer energy upon conduction, measuring these properties also allows us to better understand the factors that influence how charge carriers carry energy during charge transport. One of the remaining challenges in developing organic thermoelectric materials for practical use is the preparation of n-type thermoelectric materials, which transport electrons as their charge carrier, since most n-type organic semiconductors are unstable in air due to electron transfer to oxygen gas. We synthesized three organic conjugated polymers based on electron deficient rylene diimides and a vinylene spacer - PDNDIV, PFNDIV, and PDIV - to study how these could be doped into n-type semiconductors and how long these persist in air. Each polymer was capable of electron transport, and PFNDIV was capable of remaining n-doped with electronic charges for at least one week in air. Blending conducting fillers into organic thermoelectric materials can alter their thermoelectric properties by altering the mechanism of charge transport. We blended the conductive filler SWNT into the organic conjugated polymer PBTDV2 and measured the thermoelectric properties. Although PBTDV2 was originally developed for use as an electron transporting polymer, all blends of SWNT with PBTDV2 had p-type, hole transporting, thermoelectric properties similar to those of oxygen-doped SWNT. We measured the thermoelectric properties of two p-type organic polymers - P3HT and PDPP4T - that were doped to achieve a high concentration of charge carriers as they spontaneously de-doped and decreased their charge carrier concentration. Modeling these thermoelectric properties revealed that the spatial distribution of dopants in the polymers impacted the how much energy was carried per charge carrier due to Coulombic interactions of the dopants with the charge carriers, and that more heterogeneous spatial distributions of dopants can limit the thermoelectric performance by limiting how much energy is carried per charge carrier. These findings aid in the future development of organic thermoelectric materials by highlighting the importance of doping organic thermoelectric materials in ways that achieve homogeneous spatial distributions of dopants.