Development of Near-IR Absorbing Dyes for Conversion of Unused Solar Light

A series of zinc phthalocyanine sensitizers (PcS6-18) having different adsorption sites have been designed and synthesized to investigate the dependence of adsorption site structures on the solar cell performances in zinc phthalocyanine-based dye-sensitized solar cells. The change of adsorption sites affected the electron injection efficiency from the photo-excited dye into the nanocrystalline TiO2semiconductor as monitored by picosecond time-resolved fluorescence spectroscopy. The zinc phthalocyanine sensitizer PcS18possessing one carboxylic acid directly attached to the ZnPc ring and six 2,6-diisopropylphenoxy units showed a record PCE value of 5.9 % when used as a light-harvesting dye on a TiO2electrode under one sun condition.