Excited State Dynamics and Energy Transfer Studies of Aromatic Molecules

246 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2008.Prototypes of artificial light harvesting devices and molecular wires can be built using conjugated subunits. Electronic coupling between subunits is important for the efficiency of the energy and charge transfer events, which are the critical elements of light harvesting devices. Additionally non-radiative events can compete with the desired energy storage processes. A series of dendrimers composed of meta-conjugated phenylethynylene has been studied for use as light-harvesting devices. The non-radiative pathways for the excited states of benzene, a subunit of phenylethynylene, are studied using both ab initio and semi-empirical multiple spawning dynamics simulations, which solve the nuclear and electronic Schrodinger equations "on the fly". In this work, we also examine the effects of both meta- and para-conjugation in the ground and excited states on the electronic communication in phenylethynylenes. These studies suggest that the electronic coupling is strongly dependent on the excited state, with a large asymmetry between the excited and ground state coupling for the meta-conjugated phenylethynylenes. Using this information, a series of charge transfer molecules have been designed to test if this asymmetry could lead to fast charge separation and slow charge recombination characteristics.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD