Increased power conversion efficiency of dye-sensitized solar cells with counter electrodes based on carbon materials.

The good catalytic activity, resistance to iodine corrosion, and stability of carbon materials make them ideally suited for the fabrication of counter electrodes used in dye-sensitized solar cells (DSSCs). Different carbon materials have been used to make counter electrodes, and each has its own advantages, such as good film formation or high electric conductivity. Herein, various carbon materials were mixed and employed for preparing counter electrodes in DSSCs. Both fine film morphology and improved charge-carrier transport were obtained, and the power conversion efficiency of the DSSCs was thus increased. Accordingly, a cell efficiency of 6.29% was obtained by the DSSC with a counter electrode composed of the optimum mixture of carbon nanotubes, graphite, conductive carbon black, and graphene. Furthermore, DSSCs with a flexible counter electrode were fabricated using the optimum carbon material mixture, and the corresponding DSSCs achieved a power conversion efficiency of 4.32%.