Conjugated surfaces/interfaces

The purpose of performing calculations of physical properties parallel to experimental studies is twofold. First, since calculations by necessity involve approximations, the results have to be compared with experimental data in order to test the validity of these approximations. If the comparison turns out to be favourable, the second step in the evaluation of the theoretical data is to make predictions of physical properties that are inaccessible to experimental investigations. This second step can result in new understanding of material properties and make it possible to tune these properties for specific purposes. In the context of this book, theoretical calculations are aimed at understanding of the basic interfacial chemistry of metal-conjugated polymer interfaces. This understanding should be related to structural properties such as stability of the interface and adhesion of the metallic overlayer to the polymer surface. Problems related to the electronic properties of the interface are also addressed. Such properties include, for instance, the formation of localized interfacial states, charge transfer between the metal and the polymer, and electron mobility across the interface. 

W.R. Salaneck, S. Stafstrom, J.L. Bredas, Conjugated Polymer Surfaces, Interfaces. Cambridge University Press, Cambridge 1996. 

The synthesis of functionalized I>-B-A supramole-cules utilizing fullerenes as the acceptor unit and/or conjugated oligomers as electron donors [144—152] implies the possibility of casting such supramolecules in an oriented manner upon surfaces/interfaces. Unim-olecular diodes made from these diads has still to be realized and tested. 

Effect on Oxide—Water Interfaces. The adsorption (qv) of ions at clay mineral and rock surfaces is an important step in natural and industrial processes. SiUcates are adsorbed on oxides to a far greater extent than would be predicted from their concentrations (66). This adsorption maximum at a given pH value is independent of ionic strength, and maximum adsorption occurs at a pH value near the piC of orthosiUcate. The pH values of maximum adsorption of weak acid anions and the piC values of their conjugate acids are correlated. This indicates that the presence of both the acid and its conjugate base is required for adsorption. The adsorption of sihcate species is far greater at lower pH than simple acid—base equihbria would predict. 

Electronic Structure of Surfaces and Interfaces in Conjugated Polymers... 

By using Hg-electrode-based junctions, the electrical properties of the highly conjugated units of hexa-pen-hexabenzocoronene (HBC) have been characterized [171]. The HBC unit was anchored to the Au metal surface in an Hg-based junction by a decanonanethiol tether (C19), as depicted in Fig. 9. Comparison of the electrical behaviour of three different junctions, whose interfaces are schematized... 

J. Birgerson, M. Fahlman, P. Brom, and W.R. Salneck, Conjugated polymer surfaces and interfaces a mini-review and some new results, Synth. Met., 80 125-130, 1996. 

Salaneck WR, Staftstrom S, Bredas J-L (1996) Conjugated polymer surfaces and interfaces. Electronic and chemical structure of interfaces for polymer light emitting devices. Cambridge University Press, Cambridge... 

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