According to the June 29, 2008 issue of Science Daily, scientists have achieved a new record light conversion efficiency of 8.2% for solvent-free dye-sensitized solar cells. The new type of solar cell will make it “possible to pursue large scale, outdoor practical application of lightweight, inexpensive, flexible dye-sensitized solar films that are stable over long periods of light and heat exposure.”
While dye-sensitized solar cells have been around since the mid-90’s and have achieved efficiency rates of 11%, most dye-sensitized solar cells require the use of an electrolyte solution, which is made up of volatile organic solvents and which must be very carefully sealed. The delicate nature of the solution container stops these cells from being considered for wide-spread outdoor applications and integration into flexible structures. Also, because the volatile solvents in the electrolyte layer permeate plastic, these cells degrade over time. The new solvent free solar cells, developed by Professor Michael Graetzel of EPFL (Ecole Polytechnique Federale de Lausanne), and Shaik Zakeeruddin from the Changchun Institute of Applied Chemistry at the Chinese Academy of Sciences, use a mixture of three solid salts in place of the organic solvents. The salts are showing excellent stability and efficiency – the researchers are hopeful that further development will lead to large-scale practical applications.