Aromatic molecules are a robust and versatile platform for the development of functional materials for electronic and optical applications. Using a tandem organic synthesis / device analysis approach, we seek to determine structure-property relationships that lead to materials with exceptional performance in organic thin-film transistors (for flexible flat-panel displays), organic solar cells (for low-cost generation of electricity), organic light-emitting diodes (for high-efficiency lighting), qubits for quantum computing, and other applications. Needless to say, students in my group learn a wide range of skills, from organic synthesis to materials characterization and device fabrication.

We are also exploring new functionalization strategies to further enhance the stability of these strongly-absorbing molecules, for use in low-cost solar cells.

Materials: In collaboration with the UK X-ray crystallography facility, we have developed an excellent model that allows us to predict the solid-state order of acenes functionalized by our method - the fine-tuning allows us to make subtle changes that improve film morphology, electrode contacts or photostability. Following this model, we have prepared materials with record-high performance in a number of areas.

Transistors: A field-effect transistor is a three-electrode device that turns current between two of the electrodes (labeled "source" and "drain") off or on by application of voltage across the third electrode (called the "gate"). For use in organic transistors, we have obtained the best results using molecules that exhibit two-dimensional pi-stacking in the sold state. We collaborate with many physics and engineering research groups to discover the device performance of the materials we prepare.  For example, collaboration with the Loo group has shown new methods to control the crystal size in anthradithiophene materials, while the Jurchescu group has used spray-coating to form large-area transistor arrays with mobility as high as 5 cm2/Vs.

Solar Energy: Acenes undergo a process called 'singlet fission', which can turn one photon into two photons of roughly half the energy.  We are working on thin film materials that will convert high-energy light from the sun into double the amount of photons of lower energy, to boost the number of photons interacting with silicon solar cells. If we can do this efficiently, it will dramatically boost the power output of modern solar panels.

Quantum Computing: The singlet fission process occurs at room temperature - if we can develop materials where the singlet fission products remain stable for even a few seconds, we can uncouple quantum computing from the current constraints requiring operation at liquid helium temperatures, which will dramatically reduce the cost of these systems.

We are also exploring the use of functionalized carbon-based materials in a wide array of applications, including bio-imaging, thermoelectric power generation, radiation detection, and sensing.

I am grateful to all of my collaborators (many of whom are not mentioned on this short web page) for their insight, assistance, and for being such fantastic people to work with. I also thank the support (both intellectual and financial) of our research programs by the Office of Naval Research, the National Science Foundation, and the Department of Energy.