This book reviews the current understanding of electronic, optical and magnetic properties of conjugated polymers in both the semiconducting and metallic states. It introduces in particular novel phenomena and concepts in these quasi one-dimensional materials that differ from the well-established concepts valid for crystalline semiconductors. After a brief introductory chapter, the second chapter presents basic theore tical concepts and treats in detail the various models for n-conjugated polymers and the computational methods required to derive observable quantities. Specific spatially localized structures, often referred to as solitons, polarons and bipolarons, result naturally from the interaction between n-electrons and lattice displacements. For a semi-quantitative understanding of the various measure ments, electron-electron interactions have to be incorporated in the models; this in turn makes the calculations rather complicated. The third chapter is devoted to the electrical properties of these materials. The high metallic conductivity achieved by doping gave rise to the expression conducting polymers, which is often used for such materials even when they are in their semiconducting or insulating state. Although conductivity is one of the most important features, the reader will learn how difficult it is to draw definite conclusions about the nature of the charge carriers and the microscopic transport mechanism solely from electrical measurements. Optical properties are discussed in the fourth chapter.

Inhalt

1. Introduction.- References.- 2. An Overview of the Theory of ?-Conjugated Polymers.- 2.1 Synopsis.- 2.2 Theoretical Concepts, Models and Methods.- 2.3 The Hückel and SSH Models: Independent-Electron Theories.- 2.4 Hubbard Model: A Paradigm for Correlated Electron Theories.- 2.5 The One-Dimensional Peierls-Hubbard Model.- 2.6 The Combined Effects of Electron-Phonon and Electron-Electron Interactions: Theory and Experiment.- 2.7 Beyond Simple Models: Discussion and Conclusions.- References.- 3. Charge Transport in Polymers.- 3.1 Models for the Insulating and Semiconducting States.- 3.2 Models for Transport Processes.- 3.3 Experiments in the Insulating and Semiconducting State.- 3.4 The Semiconductor-Metal Transition and the Metallic State.- 3.5 Summary.- References.- 4. Optical Properties of Conducting Polymers.- 4.1 Elementary Considerations.- 4.2 Dielectric Response Function and Band Structure.- 4.3 Band Gap and Band Structures of Undoped Conjugated Polymers.- 4.4 Photon-Phonon Interaction.- 4.5 The Study of Elementary Excitations in Conjugated Polymers.- 4.6 Highly Conducting Conjugated Polymers.- References.- 5. Magnetic Properties of Conjugated Polymers.- 5.1 General Aspects of Magnetic Properties and Resonance Techniques.- 5.2 Structure and Lattice Dynamics of Conjugated Polymers in the Non-Conducting Phase.- 5.3 Spin Dynamics of Conjugated Defects in the Non-Conducting Phase.- 5.4 Magnetic Properties of Conjugated Polymers in the Conducting Phase.- 5.5 Magnetic Properties of Polydiacetylenes (PDA).- 5.6 Other Conjugated Polymers.- 5.7 Conclusions and Remarks.- References.