Design, Synthesis and Evaluation of Functionalized Poly (p-Phenylene Vinylene) derivates: From Existing Structures to Novel Materials

Abstract

In Chapter one, a concise description of conjugated polymers is given. Conjugated materials combine the electronic and optical properties of semiconductors with the processability and mechanical characteristics of polymers and with the readily-tailored properties of functional organic molecules. In particular the potential use of these materials in light-emitting diodes, photovoltaic cells and other opto-electronic devices has motivated the development of synthesis and processing methods of conjugated polymer materials with unique properties. Within the wide range of different classes of conjugated polymers, poly(para-phenylene vinylene) (PPV) and its derivatives are known as promising materials. Hence, we chose this existing backbone structure for the design of novel materials by applying strategies towards tailored functionalization. Specifically, we designed, synthesized and characterized non-ionic polar functionalized PPV-type polymers in order to adapt the chemical and physical properties of this conjugated material to specification. Functionalities were built in as side chains onto the phenyl groups of the PPV backbone with a variety of objectives in mind. A first objective for the polar functionalization of the PPV backbone was to find PPV-type polymers which are compatible with processing from environmentally friendly solvent systems. A second objective was to improve the performance of PPV-type materials in opto-electronic devices. Polar functionalized PPV derivatives are interesting materials for application in plastic photovoltaic cells since it is anticipated that an increased polarity leads to higher dielectric constants and therefore to an enhanced charge dissociation efficiency. In addition, tailored functionalization might lead to a better morphology and thus to an enhanced photovoltaic performance. Efforts were made to develop PPV-type material systems fitted with complex and specific functionalities for application in solar cells. Finally, also the application of functionalized PPV-type polymers as transducer layer in biosensors was within the objectives of our work. ...