Highly efficient solid-state dye-sensitized TiO2 solar cells using donor-antenna dyes capable of multistep charge-transfer cascades

Highly efficient solid-state dye-sensitized TiO2 solar cells (SDSC) that use donor-antenna dyes have been found to be capable of multistep charge-transfer cascades. Novel ruthenium dyes, Ru-TPA-NCS and Ru-TPD-NCS, with electron-donor antenna groups (triphenyl amine and tetraphenylbenzidine) were developed and applied in SDSCs. These dyes were found to display remarkably higher efficiencies of 3.4 % and 1.5 % when compared to the cell fabricated with standard N719 dye (0.7 %). The highest occupied molecular orbital (HOMO) distribution of the dyes on the antenna groups increases the spatial separation between the dye cation center and electrons injected into Ti02, retarding the charge-recombination dynamics. TPA and TPD units in the dyes also guarantee a polarity match between the relatively nonpolar HC and highly polar Ru dye, thereby improving the interfacial wetting and contact, which is very crucial for good performance.