Quinoline and Fluorene- Functionalized Porphyrins for Nanocrystalline Solar Cells

Dye-sensitized solar cell (DSC) is an electrochemical device that has two electrodes with electrolyte between them. Recently the energy conversion efficiency of DSCs using a zinc porphyrin as a sensitizer has reached >12%. However, most porphyrin dyes exhibit narrow absorption in the visible region and relatively weak absorption in the red and near-infrared region; as a result, photons in these regions are not sufficiently converted to electrons, which has been a bottle-neck for high efficiency solar cells. Additionally, the widely used benzoic acid for attaching porphyrin dyes to titanium dioxide nanoparticles tends to dissociate into electrolyte, leading to poor long-term stability. In this presentation, synthesis, characterization, photophysical properties, electrochemical and photovoltaic properties of several novel porphyrin dyes with enhanced binding strength and broader light absorption capability will be discussed. We found that 8-hydroxylquinoline-functionalized porphyrin exhibited stronger binding capacity on the titanium dioxide nanoparticle surface, broader and stronger absorption in the red region compared to conventional benzoic acid-functionalized porphyrins. We will also discuss the porphyrins that are functionalized by alkyl fluorene groups. The results demonstrate the potential of these dyes for achieving high efficiency in DSCs.