Toward More Efficient Solar Energy Conversion Using Molecularly Anchored Nanocatalysts and Novel Porphyrinoid Dyes

The scarcity and pollution of fossil fuels, together with the high cost of conventional silicon based solar cells, have motivated the development of lower-cost means of converting sunlight to electrical power. The dye sensitized solar cell (DSC) is a promising technology, with a cheap TiO2 nanoparticle film coated with dye molecules that absorb sunlight and inject excited electrons into the nanoparticles. After electrons are extracted from the TiO2 and routed through an electrical load to provide power, they are returned to the dye via electrochemical reactions involving a dissolved redox couple that surrounds the dye. While the cost of the DSC is low, there is a need to improve its efficiency, which stands at a record of 14%, about half the value for silicon solar cells. Two routes are described to improve the efficiency. One way is to reduce the energy loss in redox reactions in the device using platinum nanoparticles as nanocatalysts. This involves Pt nanoparticle synthesis, coupling of customized dyes to Pt and to TiO2, and characterization of resulting devices. The second route involves modifying strongly light-absorbing porphyrin molecules to work as dyes in DSC devices. This requires the characterization of redox and optical properties of different porphyrin dyes and chemical modification to allow attachment to TiO2 nanoparticles.