Photoelectric response mechanisms dependent on RuN3 and CuPc sensitized ZnO nanoparticles to oxygen gas.

ZnO nanoparticles were synthesized by a simple mild solution method. Spectral sensitization of nanocrystalline ZnO was carried out with [Ru(dcbpy)(2)(NCS)(2) (dcbyp = 2,2'-bipyridyl-4,4'-dicarboxylate)] (RuN3) and CuPc. The electron transfer behaviours at the surface and interface in ZnO/RuN3 and ZnO/CuPc were investigated using a surface photocurrent technique. When exposed to oxygen gas, the surface photocurrent (I(SPC)) responses of ZnO/RuN3 and ZnO/CuPc decreased and increased, respectively. The results demonstrated through the adsorption of oxygen gas that there are different microscopic mechanisms for the surface charges. The microscopic processes of electron transfer between oxygen molecules and dye-sensitized ZnO are discussed in detail in this paper. Such research should be valuable for fundamental science and optoelectronic device application of ZnO nanoparticles.