Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications

Srabanti Ghosh

• Publisher: Wiley-VCH
• Year: 2021
• Print ISBN:
  9783527345571
• Edition: 1
• eBook ISBN:
  9783527820122
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

A timely overview of fundamental and advanced topics of conjugated polymer nanostructures 

Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications is a comprehensive reference on conjugated polymers for energy applications. Distinguished academic and editor Srabanti Ghosh offers readers a broad overview of the synthesis, characterization, and energy-related applications of nanostructures based on conjugated polymers. The book includes novel approaches and presents an interdisciplinary perspective rooted in the interfacing of polymer and synthetic chemistry, materials science, organic chemistry, and analytical chemistry. 

This book provides complete descriptions of conjugated polymer nanostructures and polymer-based hybrid materials for energy conversion, water splitting, and the degradation of organic pollutants. Photovoltaics, solar cells, and energy storage devices such as supercapacitors, lithium ion battery electrodes, and their associated technologies are discussed, as well. 

Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications covers both the fundamental topics and the most recent advances in this rapidly developing area, including: 

• The design and characterization of conjugated polymer nanostructures, including the template-free and chemical synthesis of polymer nanostructures 
• Conjugated polymer nanostructures for solar energy conversion and environmental protection, including the use of conjugated polymer-based nanocomposites as photocatalysts 
• Conjugated polymer nanostructures for energy storage, including the use of nanocomposites as electrode materials 
• The presentation of different and novel methods of utilizing conjugated polymer nanostructures for energy applications 

Perfect for materials scientists, polymer chemists, and physical chemists, Conjugated Polymer Nanostructures for Energy Conversion and Storage Applications also belongs on the bookshelves of organic chemists and any other practicing researchers, academics, or professionals whose work touches on these highly versatile and useful structures. 

Part I
Design and Characterization of Conjugated Polymer Nanostructures

1
Fundamentals of Conjugated Polymer Nanostructures

Thanh-Hai Le¹ and Hyeonseok Yoon^1,2

¹Chonnam National University, Graduate School, Department of Polymer Engineering, 77 Yongbong-ro, Gwangju, 61186, South Korea

²Chonnam National University, School of Polymer Science and Engineering, 77 Yongbong-ro, Gwangju, 61186, South Korea

1.1 Introduction

Earlier research on the design and development of materials related to conjugated polymers has attracted renewed interest, which has contributed to the materials being accepted as robust alternatives to their inorganic counterparts, therefore leading to large and substantial practical research efforts. Since the time when polyacetylene was discovered in 1977 by Hideki Shirakawa, Alan Heeger, and Alan MacDiarmid, many kinds of conjugated polymers have been developed, such as polypyrrole (PPy), polyaniline (PANI), polythiophene (PT), poly(p-phenylene vinylene) (PPV), and their derivatives [1]. Conjugated polymers contain a carbon backbone, which holds interchanging single (σ) and double (π) bonds that allow electrons to be delocalized, and thus contribute towards various electronic, electrical, electrochemical, and optical characteristics. Owing to the π-conjugated system coupled with the inherent characteristics of polymers, conjugated polymers have competitive properties over those of their inorganic counterparts, such as mild synthetic conditions, chemical diversity, structural flexibility, tunable electrical/optical properties, anticorrosion, and lightweight [2, 3]. Note also that, by converting bulk conjugated polymers into nanostructures, the resulting nano-dimensionality features can lead to beneficial properties, such as quantized energy level, enlarged surface area, more efficient and rapid doping/dedoping, and enhanced crystallinity [4–7]. Conjugated polymers have been hybridized with other functional materials to overcome their limitations in terms of conductivity, stability, and solubility. These materials have been successfully utilized in a wide range of optoelectronic [8–12], energy conversion [13, 14], energy storage [15, 16], photocatalytic [4, 17], and biomedical applications [5, 18].

This chapter will present the fundamentals of conjugated polymer and their nanostructures, and focus on electronic, electrical, optical, and electrochemical properties. These properties depend on the dopants, doping level, and inherent properties of conjugated systems such as chain conformation, aggregation state, shape, and size of the nanomaterials. Better understanding of these properties and charge transport mechanisms will contribute to extending the use of conjugated polymers over a wide range of applications, from optoelectronic to medical applications, as well as in energy conversion/storage devices and systems.

1.2 Electronic and Electrical Properties

1.2.1 Conductive Mechanism

1.2.1.1 Inherent Molecular Structure

In general, energy band theory has been used to clarify the key differences between semiconductors, conductors, and insulators. The band gap is identified as being the energy difference between the lowest unoccupied molecular orbital (LUMO) of the conduction band and the highest occupied molecular orbital (HOMO) of the valence band in a material. In conductor materials, the conduction band overlaps the valence band, such that electrons are able to move freely and disseminate between the two bands. In contrast, semiconductor materials can conduct electricity under some excitation conditions because of their small band gap. When the band gap becomes too large for electrons to cross (no electricity is conducted), the material is known as an insulator. Energy band theory fails to explain why conjugated polymers, which are organic materials, can conduct electricity. The charge transport mechanisms of conjugated polymer at the molecular level have been investigated from both theoretical and experimental evidences by many research groups [19, 20]. The most commonly accepted mechanism based on the high electrical conductivity and simple chemical structure of polyacetylene is represented in Figure 1.1. In general, the existence of interchanging single and double bonds through the polymer backbone is an inherent property of conjugated polymers. These single and double bonds contain a localized σ-bond, which is known to allow formation of a strong chemical bond. Moreover, it is recognized that each double bond also holds a delocalized π-bond, which is however weaker compared with the σ-bond [21, 22]. Here, the overlap between p_z-orbitals in the chain of conjugated π-bonds allows the π-electrons to freely move across the carbon backbone. As a result, the conjugated π-bonds can conduct electricity. However, it is believed that conjugated π-bonds cannot make conjugated polymers become high-conductivity materials owing to a distinct disorder in the polymer matrix. Structural and morphological disorders hinder delocalization of π-electrons, thus delaying charge transport along the polymer chain [23–25]. Consequently, the metallic charge co...

Table of contents

• Cover
• Table of Contents
• Title Page
• Copyright
• Preface
• Acknowledgment
• Part I: Design and Characterization of Conjugated Polymer Nanostructures
• Part II: Conjugated Polymer Nanostructures for Solar Energy Conversion and Environmental Protection
• Part III: Conjugated Polymer Nanostructures for Energy Storage
• Index
• End User License Agreement