Influence of cell fabrication procedure on the performance of the dye sensitized solar cell.

The recent technological advancements of the Dye Sensitized Solar Cells (DSSCs) fabrication technology is gaining momentum as a low cost and simple fabrication technology to convert solar energy into electric energy. A systematic study of the DSSC fabrication procedure and its influence on the cell efficiency are presented in this paper. Preparation of the titanium dioxide (TiO2) layer on the working electrode was the most significant process improvement made to enhance cell efficiency. The Coatema tool was used to develop an automated TiO2 coating process, which yielded layer thicknesses with minimum micro cracks and repeatable TiO2 weight loading in the range of 8-13 microm. Secondary process improvements implemented were: vacuum drying step for the TiO2 layer, dilution ratio of the sensitized dye and sealant thickness. These optimized cell fabrication steps enhanced cell efficiencies over 200% and reduced total process time. The work in progress demonstrated higher cell efficiency slightly greater than 9% by reducing the cell size using the optimized fabrication process described in this paper. We are confident that higher efficiency cells can be fabricated with this optimized fabrication process illustrated in this paper.

Platelet deposition onto fibrin-coated surfaces under flow conditions.

Platelet deposition on fibrin-coated surfaces and release from these adherent platelets were studied in an in vitro flow system. When a mixed suspension of washed platelets and red cells flowed through a fibrin-coated glass tube, only platelets were deposited onto the fibrin-coated surfaces. The density of adhered platelets increased with flow time and decreased with distance from the tube inlet. The adhesion rate increased with increasing shear rates from 45 s-1 to 180 s-1. This adhesion process appears to fit a diffusion-limited mathematical model. Comparing with glass and other protein-coated surfaces such as collagen, fibrinogen, or albumin coated surfaces, the number of adhered platelet per unit area decreased in the following descending order: collagen, fibrin, fibrinogen, glass, albumin. On the other hand, the degree of release reaction from these platelets decreased by another order: collagen, glass, fibrinogen, fibrin. We observed little release from platelets that were in contact with a fibrin-coated surface. Our results suggest that platelets specifically adhere to fibrin-coated surface and that this interaction does not induce platelet release.