Improved properties of dye-sensitized solar cells by incorporation of graphene into the photoelectrodes

A series of dye-sensitized solar cells (DSSCs) with different graphene-P25 (G-P25) photoelectrodes were prepared by a ball milling method. The influences of graphene on the structures and performance of G-P25 cells were studied. Studies indicated that the rutile contents in G-P25 photoelectrodes increased with increasing graphene-oxide (GO) additions and reached the maximum value at GO addition of 4.5 ml. And with the increase of GO additions, the porosity of the G-P25 photoelectrodes, the interface recombination resistances, and the short current densities increased. When the GO addition was 4.5 ml, the G-P25 cells showed the best performance with the largest interface recombination resistance of 15.12 Ω and the largest photoelectric conversion efficiency of 5.09%, which was remarkably higher than those of pure P25 DSSC. Since the tendency of the photoelectric conversion efficiency varying with the GO additions was in consistence with that of the rutile contents, the enhancement of the photoelectric conversion properties of the G-P25 DSSCs was preliminary attributed to the increase of the rutile contents and the porosity in the photoelectrodes due to graphene adding.