Improved CdS QDSSCs with graphene and anatase-rutile TiO2 composite as photoanodes

In this paper, we developed a simple and convenient method for incorporating graphene with anatase-rutile TiO2 composite and applied it as photoanode to improve the photovoltaic performance of CdS QDSSCs. Our research indicated in a CdS QDSSC system, the photoelectric conversion efficiency (PCE) of anatase-rutile TiO2 (TGr0) composite photoanode was 86% higher than that rutile TiO2 NRs. We also found that the PCE increased first and then decreased with the change of graphene content after the graphene was introduced into the anatase-rutile TiO2 photoanode. When the ratio of optimized graphene/anatase TiO2 particles composite that spin-coated on rutile TiO2 NRs photoanode was 5%, we attained a maximum PCE of 2.20%, which was 178% and 50% higher than that pure TiO2 NRs (0.79%) and TGr0 (1.47%), respectively.