Electron-Accepting Organic Semiconductors
Michael Haley, Chemistry
Polycyclic hydrocarbons that possess extended pi-conjugation are of tremendous interest because of their potential use in optical and electronic device applications. While a majority of studies have focused on acenes and their derivatives, these IF - Fig8systems are susceptible to oxidative and photolytic degradation; thus, there is a pressing need for alternative, acene-like topologies. Current research in the lab is focused on molecules based on or inspired by the indenofluorene (IF) skeleton. Over the last few years, we have adapted and/or developed general methods for the assembly of a variety of fully conjugated IF derivatives and initiated exploration of their materials properties. We have shown that IFs can be prepared gram quantities in good overall yields and in excellent purity. Indenofluorenes have the potential to act as rigid, planar, electron-accepting cores for the formation of advanced materials with novel electronic properties. We are exploiting the materials potential of IFs via a combined experimental and theoretical approach, with an emphasis towards use of indenofluorenes as organic semiconductors in devices. Importantly, we demonstrated recently that single crystals of a perfluorophenyl-substituted IF could serve as an active layer in an organic field-effect transistor that exhibits ambipolar behavior.

An REU student would help construct and study additional indenofluorene scaffolds, thus further refining their design for optimal semiconductor properties. A small set of new targets would first be identified and then prepared. Given that our syntheses are modular (think molecular level Legos or Tinkertoys), most of the starting materials are readily available; thus, construction of the compounds would be straightforward. The student would characterize the new molecules by traditional techniques (NMR, IR, UV-vis, MS) as well as more elaborate methods (x-ray crystallography, fluorescence including lifetimes, EPR).