Graphene and Ag nanowires co-modified photoanodes for high-efficiency dye-sensitized solar cells

In the present work, a novel multistage structure dye-sensitized solar cell (DSSC), which consists of Ag nanowires (AgNWs), TiO2 nanoparticles and graphene wrapped TiO2 mesoporous microspheres (GTMs), was fabricated by using simple spin coating steps. The aim of this study was to modify the bandgap of GTMs by using graphene so as to promote the light absorption of GTMs in the visible light region and in turn to improve the power conversion efficiency (PCE) of DSSCs. Additionally, graphene and AgNWs can enhance the electron transfer in the DSSC to further improve the PCE of DSSCs. The effect of AgNWs and GTMs light scatting layer on the photovoltaic performance of DSSCs was investigated. The results showed that a PCE of 7.42% was achieved for the DSSC co-modified by GTMs and AgNWs, which was about twice as much as that for the DSSCs only with a TiO2nanoparticle layer (with a PCE of 3.53%). This present study might open a new avenue for the improvement of the PCE of DSSCs.