FWF - Polymer Elektronik - Polymer Electronic Devices: The role of oxidative defects

Electronic and optoelectronic components based on organic semiconductors (conjugated polymers in the present case) have been intensively studied over the past decades. The broad commercialization of some applications such as light emitting devices or simple circuits fabricated by (inkjet-)printing or soft lithography seems to be close at hand. A technologically relevant issue for industrial applications is the instability of the materials versus atmospheric influences (such as oxygen and water). Providing inert gas conditions during the fabrication process and using encapsulation schemes can solve some of the occurring problems. Still, contaminations and resulting (oxidative) defect states in the materials cannot be totally excluded (especially since some defects can already be incorporated during synthesis). The present project addresses the influence of such defects on the electronic structure of conjugated polymers. As far as fundamental research is concerned, it will be investigated under which circumstances oxidative defects lead to additional (unwanted) emission bands. The impact of the defect states on charge carrier generation and transport will be highlighted. The information gained in this part of the project will be used to assess to what extend literature data on charge carrier generation and transport are influenced by these defects. In a more technological part of the project, we will develop new strategies to either inhibit the formation or restore the already degraded materials to a more "pristine" state. To this aim e.g. oxygen getter materials will be blended into the active layer, which will serve to stabilize the devices. Defects incurred during synthesis will be "healed" using various (photo-)chemical approaches.