Suppression of recombinations in a dye-sensitized photoelectrochemical cell made from a film of tin IV oxide crystallites coated with a thin layer of aluminium oxide

A dye-sensitized photoelectrochemical cell consisting of a film of SnO₂ crystallites coated with ultrafine particles of Al₂O₃ generates an exceptionally high open-circuit voltage as compared to a cell made only from SnO₂. Al₂O₃ coating on SnO₂ improves the efficiency and the fill factor while delivering reasonably high photocurrents. Photoexcited dye molecules on Al₂O₃ injects electrons into the conduction band of SnO₂ via tunnelling through the Al₂O₃ barrier. Suppression of recombinations of electrons with the dye cations and the acceptors at the electrolytic interface build up the quasi-Fermi level in SnO₂ with an impressive increase of the open-circuit voltage.