Functionalized acenes for electronic applications

The field of organic materials has grown explosively in the past few years. Some of the most exciting of the new compounds are those intended for use in organic field-effect transistors, with the goal of providing a more cost-effective and easily-processed alternative to amorphous hydrogenated silicon. Pentacene has emerged as a leading candidate for such applications.; Pentacene is limited by its instability and insolubility, which renders it useless for solution-processing methods, the key to the promise of organic materials. In addition, the solid-state arrangement of pentacene contains only minor orbital overlap. The Anthony research group has applied a symmetric functionalization pattern to pentacene, resulting in soluble and stable semiconductors with improved orbital overlap. One of these materials has proven to be a useful transistor material, but its performance is contact-limited by its high oxidation potential.; This research project is directed towards improving the electronic properties of the first-generation materials by applying synthetic modifications that shift the energy levels. Pentacene ethers with reduced oxidation potentials were synthesized and characterized. The substitution of thiophene within functionalized acenes was also explored and resulted in a series of five- to seven-ringed analogues with interesting properties. With the help of collaborators, several of these materials were employed in various devices using solution-deposition and the resulting performance parameters are described herein, with notable successful applications to both transistors and photovoltaics.; The synthesis of six- and seven-ringed functionalized acenes with reduced bandgaps was also undertaken, culminating in a stable and soluble substituted hexacene with superior pi-overlap in the crystal. Partial characterization of a functionalized heptacene was also recorded, by the judicious application of a substitution model. The application of this model to larger acenes and acenedithiophenes was explored and limitations were discovered and detailed.