Doping in Conjugated Polymers E-Book

Pradip Kar

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: Polymer Science and Plastics Engineering
• Sprache: Englisch

Seitenzahl: 187

Veröffentlichungsjahr: 2013

Beschreibung

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.

Leseprobe

Contents

Cover

Half Title page

Title page

Copyright page

Dedication

Acknowledgement

Preface

Chapter 1: Introduction to Doping in Conjugated Polymer

1.1 Introduction

1.2 Molecular Orbital Structure of Conjugated Polymer

1.3 Possibility of Electronic Conduction in Conjugated Polymer

1.4 Necessity of Doping in Conjugated Polymer

1.5 Concept of Doping in Conjugated Polymer

1.6 Doping as Probable Solution

Chapter 2: Classification of Dopants for the Conjugated Polymer

2.1 Introduction

2.2 Classification of Dopant According to Electron Transfer

2.3 Classification of Dopant According to Chemical Nature

2.4 Classification of Dopant According to Doping Mechanism

Chapter 3: Doping Techniques for the Conjugated Polymer

3.1 Introduction

3.2 Electrochemical Doping

3.3 Chemical Doping

3.4 In-situ doping

3.5 Radiation-Induced Doping or Photo Doping

3.6 Charge Injection Doping

Chapter 4: Role of Dopant on the Conduction of Conjugated Polymer

4.1 Introduction

4.2 Charge Defects within Doped Conjugated Polymer

4.3 Charge Transport within the Doped Conjugated Polymer

4.4 Migration of Dopant Counter Ions

Chapter 5: Influence of Properties of Conjugated Polymer on Doping

5.1 Introduction

5.2 Conducting Property

5.3 Spectroscopic Property

5.4 Electrochemical Property

5.5 Thermal Property

5.6 Structural Property

Chapter 6: Some Special Classes of Dopants for Conjugated Polymer

6.1 Introduction

6.2 Iodine and Other Halogens

6.3 Halide Doping

6.4 Protonic Acid Doping

6.5 Covalent Doping

Chapter 7: Influence of Dopant on the Applications of Conjugated Polymer

7.1 Introduction

7.2 Sensors

7.3 Actuators

7.4 Field Effect Transistor

7.5 Rechargeable Batteries

7.6 Electrochromic Devices

7.7 Optoelectronic Devices

7.8 Others Applications

Chapter 8: Recent and Future Trends of Doping in Conjugated Polymer

8.1 Introduction

8.2 Doping of Nanostructured Conjugated Polymer

8.3 Doping in Conjugated Polymer Nanocomposite

8.4 Future Trends

References

Index

Doping in Conjugated Polymers

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Publishers at Scrivener Martin Scrivener ([email protected]) Phillip Carmical ([email protected])

Copyright © 2013 by Scrivener Publishing LLC. All rights reserved.

Co-published by John Wiley & Sons, Inc. Hoboken, New Jersey, and Scrivener Publishing LLC, Salem, Massachusetts. Published simultaneously in Canada.

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Cover design by Russell Richardson

Library of Congress Cataloging-in-Publication Data:

ISBN 978-1-118-57380-8

The book is dedicated to my family

Acknowledgement

I would like to express my sincere gratitude to Prof. Basudam Adhikari of the Materials Science Centre, Indian Institute of Technology, Kharagpur and Prof. Narayan C. Pradhan of the Chemical Engineering Department, Indian Institute of Technology, Kharagpur for their invaluable guidance, advice and constant inspiration. My acknowledgement is extended to Mr. Martin D. Scrivener and Scrivener Publishing LLC for this great opportunity.

Preface

The versatility of polymer materials has expanded as electroactive behavior has been included in the characteristics of some of the polymers. The most exciting development in this area is related to the discovery of intrinsically conductive polymers or conjugated polymers. Some examples are polyacetylene, polyaniline, polypyrrole, polythiophene, etc., as well as their various derivatives. The conjugated polymers which are a field of interest for researchers are also well known as “synmet” or “synthetic metal” due to the incorporation of some metallic characteristics, i.e., conductivity. Interest in this field is increasing day by day after the awarding of Nobel Prize for the discovery and development of electrically conducting conjugated polymers in the year 2000 by three scientists: Prof. Alan J. Heeger, Prof. Alan G. MacDiarmid and Prof. Hideki Shirakawa. Generally, the conductivity of these undoped conjugated polymers is 10-7-10-11 S cm-1. But for the application of conjugated polymers instead of inorganic or traditional semiconductors some higher conductivity is required. The conductivity of conjugated polymers, which are either weak semiconductors or insulators, increases by several folds due to “doping.” These conjugated polymers convert to a conductor or semiconductor from the insulator or low semiconductor by doping. Although the conductivity of doped conjugated polymers is higher than that of saturated insulating polymers, it is much less than that of conducting metals, e.g., Cu, Ag, Au, etc., and most of the doped conjugated polymers show conductivity in the semiconducting region. However, it is universally agreed that the doping process is an effective method to produce conducting polymers. As doping makes a semiconducting polymer from an insulting or low conducting one, it is of very much importance for the real applications of the conjugated polymers as semiconducting material.

The performance of doped conjugated polymers is greatly influenced by the nature of dopants and their level of distribution within the polymer. Therefore, 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 essential idea about the unusual nature of the species bearing charges, i.e., excited doped states of the conjugated systems, has been intensively discussed in the last twenty years. In this context the understanding of the nature of interaction by dopant with the π-conjugated systems is of foremost importance from the real application point of view. This rapid growth of interest in conjugated polymer-dopant interaction has been stimulated due to its fundamental importance to a cross-disciplinary section of investigators, chemists, electrochemists, biochemists, experimental and theoretical physicists, and electronic and electrical engineers. Finally, I wish to extend my sincere thanks and gratitude to all who helped me complete this project.

Pradip Kar

Chapter 1

Introduction to Doping in Conjugated Polymer

1.1 Introduction

Recently, polymers have become the most widely used, versatile material on earth. This is due to some of the advantages they have over other materials such as flexibility, tailorability, processability, environmental stability, low cost, light weight, etc. [1]. Polymers are macromolecules which are formed by the repetitive union (mer unit or repeating unit) of a large number of reactive small molecules in a regular sequence. The simplest example is polyethylene, where ethylene moiety is the “mer or repeating unit” (). A major percentage of polymers are generally made up of carbon and hydrogen atoms with a minor percentage of some heteroatoms such as nitrogen, oxygen, sulfur, phosphorous, halogens, etc. In general, polymer is more than a million times bigger with respect to its size and molecular weight than that of small molecular compounds. The properties of polymers depend on their chemical composition, molecular structure, molecular weight, molecular weight distribution, molecular forces and morphology. Even in the fifth decade of the last century polymers were well known as electrically insulating materials. In modern civilization, polymers have been used as insulating cover on electrical wire, insulating gloves, insulating switches, insulating coatings on electronic circuit boards, low dielectric coatings, etc. [1]. The so called insulating polymers generally have a surface resistivity higher than 10 ohm-cm. The polymers are insulating in nature due to the saturated covalent long-chain carbon framework structure or saturated covalent long-chain framework of carbon and some heteroatoms such as nitrogen, oxygen, sulfur, phosphorous, halogens, etc. In these polymers, the nonavailability of free electrons is responsible for their insulating behavior [2].