Panchromatic co-sensitization of porphyrin-sensitized solar cells to harvest near-infrared light beyond 900 nm

We designed a dimeric porphyrin dye (LDD1) based on an efficient push-pull zinc porphyrin (LD14) with extended pi-conjugation through coupling of two zinc porphine cores via an acetylene bridge at the meso position of the porphyrin to extend the absorption spectrum effectively into the near infrared region. The effect of dye aggregation among porphyrin molecules was significantly suppressed when the LDD1 and LD14 dyes were co-sensitized on a nanocrystalline TiO2 film in a dye-sensitized photovoltaic system. The light-harvesting ability of the device exhibits a panchromatic feature covering a broad spectral region from 400 nmto 900 nm, which results in a short-circuit current density of 21.3 mA cm(-2) and a power conversion efficiency of 10.4% in an iodine-based solar cell.