Semiconductor quantum dots exhibit unique optical characteristics such as their size-dependent band gap energy modulation regardless of their constant chemical composition. By hybridizing these quantum dots with metal oxide nanomaterials with efficient charge transport property, a photo-generated charge can be extracted via multiple charge-transfer reactions following light excitation of the quantum dot. This research aims to elucidate the underlying parameters controlling these charge transfer rates and efficiencies, and further to develop high efficiency solar cells by controlling interfacial quantum nanostructures.