Doping in Conjugated Polymers

An A-to-Z of doping including its definition, its importance, methods of measurement, advantages and disadvantages, properties and characteristics—and role in conjugated polymers The versatility of polymer materials is expanding because of the introduction of electro-active behavior into the characteristics of some of them. The most exciting development in this area is related to the discovery of intrinsically conductive polymers or conjugated polymers, which include such examples as polyacetylene, polyaniline, polypyrrole, and polythiophene as well as their derivatives. "Synmet" or "synthetic metal" conjugated polymers, with their metallic characteristics, including conductivity, are of special interest to researchers. An area of limitless potential and application, conjugated polymers have sparked enormous interest, beginning in 2000 when the Nobel Prize for the discovery and development of electrically conducting conjugated polymers was awarded to three scientists: Alan J. Heeger, Alan G. MacDiarmid, and Hideki Shirakawa. Conjugated polymers have a combination of properties—both metallic (conductivity) and polymeric; doping gives the conjugated polymer's semiconducting a wide range of conductivity, from insulating to low conducting. The doping process is a tested effective method for producing conducting polymers as semiconducting material, providing a substitute for inorganic semiconductors. Doping in Conjugated Polymers is the first book dedicated to the subject and offers a comprehensive A-to-Z overview. It details doping interaction, dopant types, doping techniques, and the influence of the dopant on applications. It explains how the performance of doped conjugated polymers is greatly influenced by the nature of the dopants and their level of distribution within the polymer, and shows how the electrochemical, mechanical, and optical properties of the doped conjugated polymers can be tailored by controlling the size and mobility of the dopants counter ions. The book also examines doping at the nanoscale, in particular, with carbon nanotubes. Readership The book will interest a broad range of researchers including chemists, electrochemists, biochemists, experimental and theoretical physicists, electronic and electrical engineers, polymer and materials scientists. It can also be used in both graduate and upper-level undergraduate courses on conjugated polymers and polymer technology.

Acknowledgement xi Preface xiii 1 Introduction to Doping in Conjugated Polymer 1 1.1 Introduction 1 1.2 Molecular Orbital Structure of Conjugated Polymer 4 1.3 Possibility of Electronic Conduction in Conjugated Polymer 7 1.4 Necessity of Doping in Conjugated Polymer 9 1.5 Concept of Doping in Conjugated Polymer 12 1.6 Doping as Probable Solution 17 2 Classification of Dopants for the Conjugated Polymer 19 2.1 Introduction 19 2.2 Classification of Dopant According to Electron Transfer 20 2.3 Classification of Dopant According to Chemical Nature 31 2.4 Classification of Dopant According to Doping Mechanism 40 3 Doping Techniques for the Conjugated Polymer 47 3.1 Introduction 47 3.2 Electrochemical Doping 48 3.3 Chemical Doping 51 3.4 In–situ doping 56 3.5 Radiation–Induced Doping or Photo Doping 59 3.6 Charge Injection Doping 61 4 Role of Dopant on the Conduction of Conjugated Polymer 63 4.1 Introduction 4.2 Charge Defects within Doped Conjugated Polymer 66 4.3 Charge Transport within the Doped Conjugated Polymer 4.3 4.4 Migration of Dopant Counter Ions 74 5 Influence of Properties of Conjugated Polymer on Doping 81 5.1 Introduction 81 5.2 Conducting Property 82 5.3 Spectroscopic Property 84 5.4 Electrochemical Property 89 5.5 Thermal Property 92 5.6 Structural Property 94 6 Some Special Classes of Dopants for Conjugated Polymer 97 6.1 Introduction 97 6.2 Iodine and Other Halogens 98 6.3 Halide Doping 103 6.4 Protonic Acid Doping 106 6.5 Covalent Doping 110 7 Influence of Dopant on the Applications of Conjugated Polymer 113 7.1 Introduction 113 7.2 Sensors 114 7.3 Actuators 118 7.4 Field Effect Transistor 120 7.5 Rechargeable Batteries 122 7.6 Electrochromic Devices 123 7.7 Optoelectronic Devices 126 7.8 Others Applications 127 8 Recent and Future Trends of Doping in Conjugated Polymer 131 8.1 Introduction 131 8.2 Doping of Nanostructured Conjugated Polymer 133 8.3 Doping in Conjugated Polymer Nanocomposite 137 8.4 Future Trends 142 References 145 Index 000

Pradip Kar obtained his PhD in 2009 from the Indian Institute of Technology, Kharagpur. He is currently an Assistant Professor in the Department of Applied Chemistry, Birla Institute of Technology, Ranchi, India, and has published more than 20 research papers in peer-reviewed journals.