Electronic and Chemical Structure of Conjugated Polymers and Model Molecular Systems

• Published in: Photonic Polymer Systems pp. 197 - 232
• Format: Book Chapter
• Language: English
• Published: United Kingdom CRC Press 1998; Taylor & Francis Group
• Subjects: Optics (light); Plastics & polymers technology; Polymer chemistry; MNA; Doping Level; Quantum Chemical Calculations; Charge; In-gap States; Conjugated Polymers; NEXAFS Spectrum; Molecular Orbitals; Ca Atoms; Polaron Band; Pristine System; Forbidden Energy Gap; Bipolaron Bands; Energy Gap; PDMS Film; Ir La; Binding Energy; Valence Band Spectra; Calculated Energy Band Structure; Sodium Doping; PTFE Film; Fermi Energy; Low Doping Level; PDMS
• ISBN: 9780824701529; 0824701526
• DOI: 10.1201/9781482269970-8

I. INTRODUCTION A. Background A description of the chemical and electronic structure of polymeric and condensed molecule solid systems is an essential ingredient in the establishment of an infor­ mation data base which could provide for the eventual use of organic molecular and polymeric materials in modem electronics applications. The single most useful experiment tool for these combined purposes has turned out to be photoelectron spectroscopy (PES) [1]. Analysis of PES data often involves the help of the results of appropriate quantum-chemical calculations [2]. A combined experimentaltheoretical approach provides a level of information output which is larger than the sum of the two [3]. Although x-ray and other structural data sometimes exist, often even the specific polymeric or molecular-geometrical parameters (atomic coordi­ nates) are provided through theoretical estimates obtained from semiempirical quantum-chemical models [4], the fine-tuning of which enables the interpretation of PES data in terms of certain geometrical parameters. In this chapter, the prin­ ciples involved in the study of the chemical and electronic structure of conjugated polymers and corresponding model molecular solids using a combination of pho­ toelectron spectroscopy and quantum-chemical calculations are reviewed. Although certain important issues are mentioned, equipment is not discussed. The theoretical models most commonly used are listed, but no comprehensive list or discussions are attempted. Instead, the emphasis is on the illustration of the type of information which may be obtained and some of the pitfalls which may occur in the process. For convenience, the examples present are taken mainly, but not exclusively, from the authors’ own works, but without compromise of the subject matter.