“As the community continues to better understand the molecular aspects that govern charge transport in organic solids, better and better materials are being prepared.”

This paper was one of the first reports of a pentacene chromophore substituted to induce pi-stacking in the solid state. Pi-stacking interactions are important for efficient charge transport, and this substituted pentacene thus yielded transistor devices with high hole mobility. More importantly, the substituents reported in this paper yielded a material that is highly soluble, allowing the formation of thin-films by solution casting. The method reported in this paper is also applicable to a wide array of technologically important chromophores, both hole and electron transporters, and has also been used to synthesize soluble versions of much larger polycyclic aromatic systems.

My group has a strong background in the synthesis of functionalized aromatic compounds, and this report was our entry into designing materials for field-effect transistors. The syntheses were pretty straightforward, and we were stunned that the molecules behaved pretty much as we expected. The work described in this paper was an excellent starting point in the exploration of substituted acenes, and has led to several great collaborations with some incredible engineers and physicists—I would count that as the biggest success arising from this project.

There are still many problems to be solved in the area of organic electronics—particularly in the use of small molecules in these applications. Improving charge injection, controlling the morphology of solution-deposited films, improving stability—these are all problems that many research groups are working on now. Our hope is to be able to combine the solution to many of these problems into a single functionalized molecule.

As the community continues to better understand the molecular aspects that govern charge transport in organic solids, better and better materials are being prepared. I think the next big leap will be the development of devices that exploit properties unique to organic semiconductors, to prepare multifunctional systems that cannot currently be fabricated from inorganic semiconductors.

  Do you foresee practical or commercial applications?

Absolutely. The properties of organic semiconductors are already at or near the specifications needed for commercial applications—it will not be long before devices run by organic field-effect transistors are commercially available.

Dr. John E. Anthony
Department of Chemistry
University of Kentucky
Lexington, KY, USA