A discovery in how to make solar cells cheap enough to boost the use of solar energy looks promising according to experts. The design represents an inexpensive process making use of an organic, printed dye to absorb sunlight. The study, reported in Science magazine, is seen as a welcome step forward in the search for cheaper, efficient, solutions for solar energy.
Electrochemist Michael Graetzel at the Swiss Federal Institute of Technology in Lausanne, who back in 1991 had devised a dye-sensitized solar cell (DSC),and his team are credited with sidestepping a roadblock that prevented DSCs from becoming commercially viable.
Researchers and manufacturers were using the rare and expensive metal ruthenium (ru)in the dyes and could get only low voltages in the cells Graetzel invented back in 1991. Between both issues of lower cell efficiency and higher costs of ruthenium, there was work to be done. Now Graetzel and his colleagues believe they have found sound alternatives to the expensive dyes and iodide mediators limiting voltage.
They chose a zinc-bearing compound similar to chlorophyll to build a newer type of solar cell. For dyes, they use molecules consisting of a group that loses electrons, a group that accepts them, and a unit that has a light-absorbing group similar to that in chlorophyll. DSCs in their current design enable an efficiency of 12.3 percent. They hope to achieve efficiencies of 15 percent. That would render a more realistic alternative to semiconductor-based photovoltaics.