Münster 1999 – wissenschaftliches Programm

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O: Oberflächenphysik

O 45: Hauptvortrag

O 45.1: Hauptvortrag

Dienstag, 23. März 1999, 16:15–17:00, PC4

Oligomeric model studies of the conjugated polymer/metal interface. — •Michael Ramsey — Karl-Franzens University Graz,Institut fuer Experimentalphysik, A-8010 Graz, Austria

With well defined, in-situ prepared, oligomeric model molecule systems, surface science spectroscopies provide direct means of studying the electronic and interface properties of active organic materials. This will be illustrated with results of phenyl and thiophene oligomers as models for the so-called conducting polymers. Direct evidence for the electronic states (UPS,IPES) and quinoidic structure (HREELS) associated with (bi)polarons, formed by charge transfer doping at the alkali metal interface, will be presented. If functional organic materials are to live up to their promise as active elements in devices a better understanding, and control, of their interface properties is required. With examples of bithiophene on a variety of clean and modified single crystal surface it will be shown that the geometric structure and band alignment at the interface can be tailored. Consideration of the band alignment on the one hand clearly demonstrates a number of fallacies that have determined the choice of device contacts up till now and, on the other hand, suggests that the vacuum level is a meaningful and useful energy reference level. *Supported by Austrian Science Foundation SFB: Electroactive Materials.