Molecular Design Of Doped Polymers For Thermoelectric Systems Final Technical Report

The self-assembly of organic semiconducting molecules and polymers is critical for their electrical properties. This project addressed the design of organic semiconductors with novel synthetic building blocks for proton-dopable conducting materials and the molecular order and microstructure of high performance semiconducting polymers blended with charge transfer dopants. Novel azulene donor-acceptor materials were designed and synthesized with unique electronic effects upon protonation to generate charged species in solution. The microstructure and optical properties of these derivatives were examined to develop structure-property relationships. Studies of the microstructure of blends of charge transfer doped semiconducting polymers revealed highly ordered conductive phases in blends. The molecular packing of one blend was studied in detail using a combination of solid-state NMR and x-ray scattering revealing that dopant incorporation is unlikely to be random as assumed in transport models. Studies of the electrical properties of these highly ordered blends revealed a universal trend between the thermopower and electrical conductivity of semiconducting polymers that is independent of the doping mechanism.

This book summarises the significant progress made in organic thermoelectric materials, focusing on effective routes to minimize thermal conductivity and maximize power factor.

This book provides an overview of chemical vapor deposition (CVD) methods and recent advances in developing novel materials for application in various fields. CVD has now evolved into the most widely used technique for growth of thin films in electronics industry. Several books on CVD methods have emerged in the past, and thus the scope of this book goes beyond providing fundamentals of the CVD process. Some of the chapters included highlight current limitations in the CVD methods and offer alternatives in developing coatings through overcoming these limitations.

The field of semiconducting polymers has attracted many researchers from a diversity of disciplines. Printed circuitry, flexible electronics and displays are already migrating from laboratory successes to commercial applications, but even now fundamental knowledge is deficient concerning some of the basic phenomena that so markedly influence a device's usefulness and competitiveness. This two-volume handbook describes the various approaches to doped and undoped semiconducting polymers taken with the aim to provide vital understanding of how to control the properties of these fascinating organic materials. Prominent researchers from the fields of synthetic chemistry, physical chemistry, engineering, computational chemistry, theoretical physics, and applied physics cover all aspects from compounds to devices. Since the first edition was published in 2000, significant findings and successes have been achieved in the field, and especially handheld electronic gadgets have become billion-dollar markets that promise a fertile application ground for flexible, lighter and disposable alternatives to classic silicon circuitry. The second edition brings readers up-to-date on cutting edge research in this field.

Thermoelectrics for Power Generation - A Look at Trends in the Technology is the first part of the InTech collection of international community works in the field of thermoelectric power generation. The authors from many counties have presented in this book their achievements and vision for the future development in different aspects of thermoelectric power generation. Remarkably, this hot topic unites together efforts of researchers and engineers from all continents of our planet. The reader will find in the book a lot of new interesting information concerning prospective materials for thermoelectric generators, both inorganic and organic; results of theoretical studies of materials characteristics; novel methods and apparatus for measuring performance of thermoelectric materials and devices; and thermoelectric power generator simulation, modeling, design, and practice.

Intrinsically conducting polymers forms a category of doped conjugated polymers that can conduct electricity. Since their discovery in the late 1970s, they have been widely applied in many fields, ranging from optoelectronic devices to biosensors. The most common type of conducting polymers is poly(3,4-ethylenedioxythiophene), or PEDOT. PEDOT has been popularly used as electrodes for solar cells or light-emitting diodes, as channels for organic electrochemical transistors, and as p-type legs for organic thermoelectric generators. Although many studies have been dedicated to PEDOT-based materials, there has been a lack of a unified model to describe their optical properties across different spectral ranges. In addition, the interesting optical properties of PEDOT-based materials, benefiting from its semi-metallic character, have only been rarely studied and utilized, and could potentially enable new applications. Plasmonics is a research field focusing on interactions between light and metals, such as the noble metals (gold and silver). It has enabled various opportunities in fundamental photonics as well as practical applications, varying from biosensors to colour displays. This thesis explores highly conducting polymers as alternatives to noble metals and as a new type of active plasmonic materials. Despite high degrees of microstructural disorder, conducting polymers can possess electrical conductivity approaching that of poor metals, with particularly high conductivity for PEDOT deposited via vapour phase polymerization (VPP). In this thesis, we systematically studied the optical and structural properties of VPP PEDOT thin films and their nanostructures for plasmonics and other optical applications. We employed ultra-wide spectral range ellipsometry to characterize thin VPP PEDOT films and proposed an anisotropic Drude-Lorentz model to describe their optical conductivity, covering the ultraviolet, visible, infrared, and terahertz ranges. Based on this model, PEDOT doped with tosylate (PEDOT:Tos) presented negative real permittivity in the near infrared range. While this indicated optical metallic character, the material also showed comparably large imaginary permittivity and associated losses. To better understand the VPP process, we carefully examined films with a collection of microstructural and spectroscopic characterization methods and found a vertical layer stratification in these polymer films. We unveiled the cause as related to unbalanced transport of polymerization precursors. By selection of suitable counterions, e.g., trifluoromethane sulfonate (OTf), and optimization of reaction conditions, we were able to obtain PEDOT films with electrical conductivity exceeding 5000 S/cm. In the near infrared range from 1 to 5 µm, these PEDOT:OTf films provided a well-defined plasmonic regime, characterized by negative real permittivity and lower magnitude imaginary component. Using a colloidal lithography-based approach, we managed to fabricate nanodisks of PEDOT:OTf and showed that they exhibited clear plasmonic absorption features. The experimental results matched theoretical calculations and numerical simulations. Benefiting from their mixed ionic-electronic conducting characters, such organic plasmonic materials possess redox-tunable properties that make them promising as tuneable optical nanoantennas for spatiotemporally dynamic systems. Finally, we presented a low-cost and efficient method to create structural colour surfaces and images based on UV-treated PEDOT films on metallic mirrors. The concept generates beautiful and vivid colours through-out the visible range utilizing a synergistic effect of simultaneously modulating polymer absorption and film thickness. The simplicity of the device structure, facile fabrication process, and tunability make this proof-of-concept device a potential candidate for future low-cost backlight-free displays and labels.

While there is information available in handbooks on polythiophene chemistry and physics, until now, few if any books have focused exclusively on the most forwardly developed electrically conductive polymer, Poly (3,4-ethylenedioxythiophene)-otherwise known as PEDOT. This resource provides full chemical, physical, and technical information about this important conducting polymer, discussing basic knowledge and exploring its technical applications. Presented information is based on information generated at universities and through academic research, as well as by industrial scientists, providing a complete picture of the experimental and the practical aspects of this important polymer.