The electrochemical Dye Solar cell was invented in 1988 by Professor Graetzel of Lausanne Polytechnique, Switzerland. The “Graetzel” dye cell is based on a layer of nano-sized titanium dioxide particles impregnated with dye. Dye cells have been a subject of intense academic interest as more than 50 university research teams around the world have worked to enhance their lifetime, size and efficiency.
Dye cells generate electricity from solar energy using nano-sized titanium dioxide particles impregnated with dye, rather than silicon or similar semiconductors. Using DSCs will result in unprecedented low costs, both manufacturing line capital cost and module cost per peak watt (ppw). Other solar cell technologies (silicon, thin film) rely on complex vacuum deposition techniques for cell active layer preparation. Not only is the production line for these systems large, complex and very expensive, but the raw materials (such as silicon) are costly and undersupplied. By comparison, dye requires simple equipment (screen printing, air ovens) and benign materials like Titania powder available at low cost.
This is a schematic depiction of the components and operating mechanism of a typical PV dye cell. The photoanode (facing the light source) is a glass plate whose inner surface has been coated with a thin layer (0.5 micron) of transparent conducting tin oxide (TCO). Onto this layer is coated (e.g. by sintering, other low temperature methods are available such as Electrophoresis) a several micron thick porous layer of nanocrystalline titanium dioxide (particle size about 20 nanometers) on which a monolayer of sensitizer dye is absorbed (ruthenium complex). The cell also comprises electrolyte containing a redox species based on iodide/tri-iodide, and a counter electrode (cathode) consisting of a glass plate also with a conducting tin oxide layer, coated with a few mono-layers of catalyst (platinum was originally used and can be replaced with carbon-based alternatives). In our approach the carbon layer can be applied directly on the Titania. This eliminates the need for a second sheet of FTO glass in the cell.
Courtesy of 3GSolar.