There are few sights as lovely as a diatom. Single-celled, photosynthetic algae with intricate skeletons made of pure silica, they fascinated famous 19th century German zoologist Ernst Haekel, who painted this illustration in oils. Recently they have also become fascinating to scientists developing biologically-based solar panels.
Diatoms are ecological workhorses. For at least 100 million years they have formed the basis of oceanic food chains. They fix nearly a quarter of atmospheric CO2. (Rising acidity in oceans may affect their populations).
At Oregon and Portland State Universities, researchers are advancing the relatively new thin-film, dye-sensitized solar cells using diatoms' ready-made structural complexity. First, a transparent, conductive glass surface is coated with diatoms. Their organic matter is removed, leaving the skeletons, which are then impregnated with a nanoparticle solution containing highly absorbtive, photo-sensitive dye molecules and the semiconductor titanium dioxide.
The nanostructure of diatom skeletons increase the interaction between incoming photons and the dye molecules. Dye-sensitized solar is relatively environmentally safe, and scientists expect using the ready-made diatom shells will make the technology up to three times more efficient, and much cheaper.