(546f) Improving Photoactive Surface Area of Dye-Sensitized Solar Cells through Supercritical Fluid Dye Penetration

While the benefits of solar cells are clear, these new technologies remain relatively expensive and inefficient. Dye-sensitized solar cells (DSSCs) are promising alternatives but photon collection and electron generation are dependent on the optical density of the film. Due to an inherent absence of an electric field within the nanoparticles, trapping affects charge carrier transport and back reactions such that diffusion coefficients and lifetimes react in opposition. This effect places an upper limit on the nanoparticle film thickness and the amount of absorbed light. Since film thickness cannot be increased in nanoparticle-based DSSCs, dye uptake becomes important in determining conversion efficiencies. Dye insertion through wet chemical or gas phase approaches are subject to capillary forces and condensation leading to inefficient coating of the titania nanostructures. Supercritical fluids (SCFs) cannot be condensed to a liquid phase minimizing these problems. Here we present the performance of DSSCs based on SCF impregnation of N-719 and N-749 (black dye). The better impregnation and coating of the titania may reduce back reactions, thereby enabling thicker titania films to be utilized. We also describe new methods to prepare thick, defect-free titania films and a non-destructive method to quantify the adsorption of dye.