Photophysical and Photochemical Processes in Small Molecules and Materials for Solar Energy Conversion

The work covered in this thesis all falls under the theme of photophysical processes after light and matter interact. Those of primary interest are Raman scattering induced vibrations and excited state dynamics probed by transient absorption spectroscopy. Small molecules are studied with Raman spectroscopy and computational chemistry. These studies unearth the shifts in vibrational frequency as a function of charge transfer or receipt and how a quantitative assay of natural orbital populations and delocalization can offer both the nature and magnitude of this charge transfer. Further, a method is presented that builds upon previous work within the academic family tree; within this study, a method for enhancing Raman scattering while a molecule is frozen in ice and submerged in liquid nitrogen. Transient absorption spectroscopy is used to initiate an electron transfer within a dye adhered to a semiconductor surface in dye-sensitized solar cell devices. This technique is used to track the evolution and regeneration of the dye cation through changes in absorption spectra of the excited state relative to that of the ground state. These studies yield evidence that manipulating dye sterics to inhibit negative processes within the solar cell device has drastic impacts on efficiency and kinetics