Scientists found a method to change spatial arrangement of bipyridine molecules on a surface, according to a study published on October 9, 2018.
This study was conducted by the scientists at the University of Basel. These potential components of dye-sensitized solar cells form complexes with metals and thereby alter their chemical conformation.
Although energy yield of dye-sensitized solar cells are not very satisfactory, it has been considered a sustainable alternative to conventional solar cells for many years. By using tandem solar cells, the efficiency of these cells can be increased. The way in which the dye, which absorbs sunlight, is anchored to the semiconductor plays a crucial role in the effectiveness of these solar cells. However, the anchoring of the dyes on nickel oxide surfaces, which are particularly suitable for tandem dye-sensitized cells, is not yet sufficiently understood.
Scientists from the Swiss Nanoscience Institute and the Departments of Physics and Chemistry at the University of Basel conducted a detailed research on how single bipyridine molecules bind to nickel oxide and gold surfaces.
Bipyridine crystals served as an anchor molecule for dye-sensitized cells on a semiconductor surface. This anchor binds the metal complexes, which in turn can then be used to bind the various dyes. By using scanning probe microscopes, it was found that bipyridine molecules bind flat to the surface in their trans configuration initally. The addition of iron atoms and an increase in temperature cause a rotation around a carbon atom in the bipyridine molecule and thus leads to the formation of the cis configuration.