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 accepters at the electrolytic interface build up the quasi-Fermi level in SnO2 with an impressive increase of the open-circuit voltage.