Interparticle charge transfer in dye-sensitized films composed of two kinds of semiconductor crystallites

Interparticle charge transfer between different types of semiconductor crys tallites in contact on band gap excitation or dye-sensitization is document ed. The general consensus had been that electrons always transfer from part icles of higher conduction band position to those with lower conduction ban d position. Observation on dye-sensitizated photoelectrochemical cells made from SnO2/ZnO films sensitized with different dyes suggests that the elect ron transfer could occur in either direction, that is from semiconductor of high band position to the semiconductor of the low band position or vice v ersa, depending on which surface adsorbs the dye more strongly. (C) 2001 Ac ademic Press.