Electron injection model for graphene-induced efficiency enhancement in dye-sensitized solar cells

A model, correlating the reduced graphene oxide (rGO)-induced shrinking of the bandgap in rGO/TiO2 composite films to the efficiency enhancement in associated dye-sensitized solar cells, is proposed. The intercalated rGO nanosheets into TiO2 cause redistribution of the density of states (DOS) and modification of the energetics. The DOS increases with rGO proportion, [rGO], and the conduction band (CB) edge moves into the gap to regain the initial critical DOS for a mobility edge. The rate of electron injection from the dye increases proportionally to the DOS, thus enhancing the DSSC efficiency.