New perylenes for dye sensitization of TiO2

We describe a new generation of perylene photosensitizers based upon N-(2,5-di-tert-butylphenyl)perylene-3,4-dicarboximide. The new sensitizers have more favorable energetics for electron injection into TiO2 and better light absorption properties for solar conversion than previous sensitizers based upon perylene tetracarboxylic acid dianhydride. Syntheses, absorption properties, and electrochemical potentials for the new perylenes are reported. We compare the solar conversion efficiencies of the dyes in the dye sensitized solar cell (DSSC) and discuss trends in terms of energetics and structural differences that may affect the injection and recombination processes. These are the highest efficiencies yet reported for perylene sensitizers in the DSSC.