CdS and PbS quantum dots co-sensitized TiO2 nanorod arrays with improved performance for solar cells application

In this paper, we report a novel CdS and PbS quantum dots (QDs) co-sensitized TiO2 nanorod arrays photoelectrode for quantum dots sensitized solar cells (QDSSCs). TiO2 film consisting of free-standing single crystal nanorods with several microns high and 90–100 nm in diameter were deposited on a conducting glass (SnO2:FTO) substrate by hydrothermal method. Then CdS/PbS QDs were deposited in turn on TiO2 nanorods by facile SILAR technique. The FTO/TiO2/CdS/PbS, used as photoelectrode in QDSSCs, produced a light to electric power conversion efficiency (Eff) of 2.0% under AM 1.5 illumination (100% sun), which shows the best power conversion efficiency compared with single CdS or PbS sensitized QDSSCs. One dimension TiO2 nanorod provides continuous charge carrier transport pathways without dead ends. The stepwise structure of the band edges favored the electron injection and the hole-recovery for both CdS and PbS layers in photoelectrode, which may gave a high electric power conversion efficiency. The facile preparation and low cost nature of the proposed method and structure make it has a bright application prospects in photovoltaic areas in the future.