Photoinduced charge separation in photonic materials

The research contained within involves the study of basic electron and energy transfer reactions in fluid solution and a wide variety of heterogeneous media including gel materials, colloids, and thin films. These processes were investigated primarily by time-resolved photoluminescence (PL) and absorption spectroscopy, along with steady-state PL measurements.; In fluid solution, Cu(I) diimine metal-to-ligand charge transfer (MLCT) excited states were shown to undergo energy and electron transfer processes. This work represents the first direct spectroscopic evidence of this Cu(I) excited state chemistry.; The photophysics of Ru(II) polypyridyl compounds were explored in insulating {dollar}rm SiOsb2{dollar} gel materials. The time-resolved PL decays of these encapsulated compounds were complex under all conditions and were modeled by discrete and distribution models. This work was the foundation for electron and energy transfer studies of {dollar}rm Ru(bpy)sb3sp{lcub}2+{rcub}{dollar} in the same material. It was shown that electron and energy transfer processes in solution could be readily translated into insulating gel materials and that the reactions in gels largely resemble that which take place in solution.; Transparent {dollar}rm TiOsb2{dollar} gels were synthesized and the excited state behavior of these materials were characterized. It was found that trapped electrons could be generated with UV excitation of these materials and that these electrons reduce other chemical species external to the gel network.; Large gains in charge separation lifetimes were gained in utilizing phenothiazine electron donors in conjunction with dye sensitized {dollar}rm TiOsb2{dollar} colloids and thin films. A novel Ru(II) sensitizer containing a covalently bonded phenothiazine donor anchored to {dollar}rm TiOsb2{dollar} materials results in remarkably long-lived charge separated states.; Dye sensitization of {dollar}rm TiOsb2{dollar} capped {dollar}rm SnOsb2{dollar} nanoparticles results in a 2-3 order of magnitude increase in charge separation over lifetimes obtained for sensitized {dollar}rm TiOsb2.{dollar} This work represents the first studies of dye sensitization in capped semiconductor colloids.