UC Berkeley

Highly structured nanomaterials offer promise to revolutionize numerous areas of energy conversion technology. Many of the best designs are hybrid systems involving mixed domains of organic materials, organic/inorganic contacts, and important energy transfers between these different materials. While much attention has focused on 10's of nm length scale structuring of these systems, the actual atomistic detail of the interfaces between molecules and between molecules and inorganic interfaces is also important. In this dissertation we explore the excited states of molecules and the changes in these states at interfaces with a range of ab initio theoretical methods. We examine the accuracy of both high level theory and efficient approximations in the treatment of interfacial and environmental effects. Additionally we draw initial design guidance for further applications in nanoscience from our results. Specifically we consider the electron addition and removal energies of small molecules, a fundamental building block if we want to understand more complex systems, the neutral excitations of small donor/acceptor complexes, the alteration of electron additional and removal energies for molecules bound to semiconductors and their alignment with the semiconductor band edges, and the effect of interfacial driven charging on the vibrational spectrum of a molecule in a metallic single molecule junction.