Solving a Solar Cell Problem
While people are interested in solar power as a way to provide clean power, researchers are interested in solar power because of its many limitations. Solar panels are not cheap to make, not very efficient, are fragile, and many designs require toxic or rare materials. Each of these issues makes it harder to implement solar power in a meaningful way, but researchers at Northwestern University have solved a problem with one design that may overcome the limitations of other designs.
Grätzel cells are cheap and environmentally safe solar cells that have the disadvantage of leaking. Unlike most other solar cell designs, this one utilizes a liquid electrolyte to absorb and convert sunlight into electricity. Unfortunately the liquid can leak out and actually corrode the solar cell, which prevents the cell from lasting more than eighteen months. The Northwestern researchers solved this problem by replacing the traditional liquid with a liquid that dries into a solid, similar to how paint dries.
The new dye is made of cesium, tin, and iodine (CsSnI3) and is actually poured into the cell, where it then envelopes millions nanoparticles. These nanoparticles have a precise diameter of 20 nm to maximize their surface area. The more surface area coated with the dye the more sunlight can be collected. As the solar cell achieved 10.2% efficiency, which is the highest efficiency for a solid-state cell using a dye sensitizer, this strategy appears to have worked.
Technically though, this is not a Grätzel cell, because certain elements of the design deviate too much from that design. However the successes here may enable new successes with other solar cell designs that will be high efficiency, cheap, and safe for the environment.