A Novel Meso-Linked Porphyrin Sensitized Solar Cell

  • Dr Joanne Dy, Research Center for Advanced Science and Technology, The University of Tokyo, Japan
  • Dr Koichi Tamaki, Research Center for Advanced Science and Technology, The University of Tokyo, Japan
  • Dr Yoshitaka Sanehira, Japan
  • Dr Jotaro Nakazaki, Research Center for Advanced Science and Technology, The University of Tokyo, Japan
  • Prof Satoshi Uchida, Research Center for Advanced Science and Technology, The University of Tokyo, Japan
  • Prof Takaya Kubo, Japan
  • Prof Hiroshi Segawa, Japan

    • The dye-sensitized solar cell (DSSC) is a promising candidate for the next-generation low-cost renewable energy device. For the typical DSSC, ruthenium-based dyes on TiO2 have been used and produced up to 10% photoelectric conversion efficiency (η), thus fueling the search for new high efficiency dyes.

    Porphyrin, which is similar in structure to chlorophyll, is well-known for its strong light absorption that allows it to participate in energy and electron transfer processes. This macrocyclic ring possesses a large π-conjugation that reduces the HOMO-LUMO energy gap attractive for photosynthetic mimics, and electronic and photonic applications. Another feature of porphyrin is the facile functionalization of its meso and β positions, which can be exploited to fine-tune its electronic properties. Several porphyrin monomers have been previously used in DSSC and were reported to give reasonable performance. However, the DSSC properties of porphyrin arrays are yet to be explored. Herein, we report three meso-linked porphyrin dimers as potential sensitizers for nanocrystalline TiO2 DSSC.

    Bis-freebase (J1), mono-zinc inserted (J2) and bis-zinc inserted dimers (J3) were prepared by Suzuki coupling of their respective monomeric components. The conversion efficiency increased according to the number of zinc-inserted atoms: J1<J2<J3 (1.5%, 1.7%, 2.3% under AM 1.5 solar irradiation). In addition, the zinc-inserted compounds gave IPCE peaks of ~60% while the freebase dimer only reached a maximum IPCE of 30%. Considering these values, meso-linked porphyrin dimers are attractive candidates for DSSC applications. Optimization of the DSSC fabrication conditions may further increase the conversion efficiencies and are currently underway.