In this study CdS and CdSe quantum dot sensitized solar cells (QDSCs) were fabricated using a double layer electron transport TiO2 scaffold. This mesoporous film was composed of a nanocrystalline TiO2 layer decorated with an interestingly formed TiO2 nanorods (NRs) over-film. The nanorods layer were hydrothermally grown on the basis of the underlying TiO2 nanoparticles and grown on random directions with interfaces which were clearly shown in the SEM images. The main target was to obtain the maximum ability of energy conversion for the QDSC with proposed photoanode structure. The thickness of transparent nanocrystalline sublayer and overgrown TiO2 NRs were measured about 5.0 and 2.0 lm, respectively. The CdS QDs film was deposited through successive ionic layer adsorption and reaction technique. The CdSe film was also efficiently formed in a short time by chemical bath deposition method. The back-recombination blocking ZnS and SiO2 layers were also applied for higher improvement. The cells were finally assembled using polysulfide electrolyte and CuS counter electrode. Different structural and optical analyses were performed at different stages on the photoanodes and finally the photovoltaic characterizations were carried out. The QDSCs were fabricated with and without CdSe and SiO2 films to show the effect of double sensitization and passivation. According to the results, the CdSe co-sensitizing QDs layer could improve the power conversion efficiency of the cells up to 19%. Besides, the SiO2 second passivating film could enhance the photovoltaic performance by 17% based on the performed measurements. The maximum efficiency was finally obtained about 3.7% and belonged to the QDSC with TiO2 NCs/NRs/CdS/CdSe/ZnS/ SiO2 photoanode structure. This could be justified and compared with the performance of other photoanode structures based on the lower surface area but the higher light scattering in this double layer nanostructured TiO2 scaffold.
