Charge Delocalization and Mobility in Ground and Photoexcited States of Conjugated Pi-Systems Incorporating MM Quadruple Bonds (MM=Mo2, MoW and W2)

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The Chemical Structure, Dynamics and Mechanisms B Program of the Chemistry Division supports Professor Malcolm Chisholm of the Ohio State University to synthesize new molecular materials for photon harvesting and photovoltaic applications. The syntheses will incorporate metal-metal quadruply boded unit units (M = Mo or W) into conjugated organic units, with the ultimate intent that the materials will absorb sunlight across the entire visible and near-infrared region of the solar spectrum by metal to ligand charge transfer. The photo- excited states will be investigated by ultra-fast spectroscopy to determine the lifetimes and charge distributions in the singlet and triplet states. Computational methods will be employed in the design of the new materials and their characterization will employ detailed electrochemical studies to aid in the elucidation of electron and hole mobility. Finally, the application of these new materials for photovoltaic devices will be explored through collaborations with colleagues in the Departments of Physics and Electrical Engineering.Photon harvesting to make electricity is an important emerging technology. It is already greatly influencing the energy market place as a sustainable and greener alternative to the use of fossil fuels. The use of solid-state inorganic materials is a rapidly maturing area, while that of devices employing inexpensive organic materials is one that is emerging over the past decade to compete with efficiencies now reaching better that 12%. It is to this emerging area that the new materials from this research will contribute. The work to be carried out by graduate students will give them a demanding training in syntheses and spectroscopic techniques as well as being part of a multidisciplinary program in photovoltaics involving collaborations with persons in physics and electrical engineering. The topic of solar energy harvesting is one of great public interest and in addition to publications in scientific journals we will engage high school students and the general public in demonstrations and talks.