Synthesis and characterization of carbon-based materials for electronics and composites.

摘要

Organic based materials have become an increasingly important area of research and have already seen initial commercial applications in organic light-emitting diodes. These organic based materials are much cheaper and easier to process into devices than existing inorganic materials. The leading class of organic electronic materials is the acenes, the linearly fused class of aromatic compounds.; For use in transistors, pentacene is the dominant organic material for its electronic properties that rival hydrogenated amorphous silicon, but pentacene is extremely insoluble and unstable in the presence of air. One of the research goals was preparing pentacene derivatives with increased stability and solubility and HOMO-LUMO levels on par with pentacene without using ethynyl substituents as was done previously in our research group. Dioxolane substituted pentacenes were prepared and the solid-state orientation and electronic properties of these materials were investigated. This was a preliminary investigation and opened the door to the possibility of a new class of pentacene derivatives.; A separate study related to acenes was also undertaken to develop and study a new tellurium-mediated cycloaromatization reaction. This study resulted in a low temperature, scalable cycloaromatization reaction when compared to the thermal cycloaromatization reaction. The scope of this reaction was also studied, which included various functionalized aromatic enediynes.; A series of ethynylated anthracene derivatives with varying degrees of solid-state pi-interactions were prepared and the structure-property relationships of these materials in organic light-emitting diodes were investigated. These materials resulted in blue and green emissive devices, with the highest efficiency devices resulting from the materials with the least amount of pi-interaction.; Another area of research that was pursued was the preparation of carbon nanotube composites. This was an attempt to functionalize the sidewalls of multi-walled nanotubes in order to better incorporate the nanotubes into a polystyrene matrix. These functionalized nanotubes did result in composites that were stronger than the original polystyrene and composites prepared from raw nanotubes.