Toshiba Corp. (New York, NY) announced a major breakthrough in solar cells that is expected to produce simpler, low-cost cell production and significantly extended scope of application for solar cells. Toshiba has successfully solidified electrolytes, the key material of organic-dye-based solar cells, ending the potential hazard of leaks of liquid electrolyte. Cells would offer a solar-energy conversion efficiency of 7.3 percent and be formed on a plastic substrate, opening up the way to a wide range of new applications for solar cells.
Organic-dye-sensitized solar cells are widely recognized as a promising replacement for conventional silicon-based solar cells, which are expensive to produce, susceptible to damage from impurities, inherently nontransparent, poorly suited to installation on windows and their use on small products is limited. Organic-dye-sensitized solar cells are transparent, easier to manufacture and cheaper to produce.
Toshiba has isolated and identified chemicals that support electrolyte solidification while allowing retention of the current manufacturing process. Toshiba has tested its solidified electrolyte to a temperature of 120 degrees centigrade, more than enough for practical application, and posits that it will not melt before thermal decomposition at around 250 degrees centigrade. This breakthrough also allows cells to be formed on a plastic substrate. Such cells are between 20 and 50 percent lighter than those formed on glass. In the experimental cells, electrolyte is inserted between a titanium dioxide layer and a transparent counter electrode, and can be solidified at room temperature or at a faster rate by exposure to a higher temperature. This new process allows the layer to be fabricated on plastics or thin organic films while maintaining its energy-conversion efficiency.
Toshiba's patent application for the chemicals is pending, and the company expects to start licensing the technology to interested parties this summer.
Details of the new process will be announced May 2, 2000, at the 16th European Photovoltaic Solar Energy Conference and Exhibition in Glasgow, Scotland.