ZnO Nanoparticles-CdS Quantum Dots/N3 Dye Molecules: Dual Photosensitization

We developed dual photosensitization, in which US quantum dots serve as a sandwich layer between the ZnO nanoparticles (NPs) and N3 dye molecules, alleviating the serious issues of CdS photocorrosion and the Zn2+/N3 dye complex formation leading to insulating surface aggregation. The improvement in the solar-to-electrical conversion efficiency from 0.11 and 0.85 to 3.04% when compared to ZnO/N3 and ZnO-CdS, respectively, is attributed to the effective coupling between the ZnO NPs/N3 dye molecules in the presence of US QDs, which in turn enhances the rate of electron injection due to the faster electron injection and transfer rate. Strong ZnO NPs-CdS QDs linking is explored systematically using UV-vis spectroscopy and is interpreted with a charge transfer resistance obtained from impedance spectroscopy studies.