Novel self-Assembly with zinc porphyrin via axial coordination for dye-sensitized solar cells

Two zinc porphyrins substituted at the meso-positions with different donor units (denoted as ZnP1 and ZnP2) have been designed and synthesized to construct new self-Assemblies (denoted as ZnPx-ZnPA) with anchor porphyrin (ZnPA) dyads formed by the coordination bonds of Zn-To-ligand approach. Then these assemblies were absorbed on the semiconducting TiO₂ electrode surfaces by the carboxylic groups of anchor porphyrin (ZnPA) to build dye sensitized solar cells. Their spectral properties, electrochemical, theoretical calculations and photovoltaic properties were systematically investigated. Interestingly, these self-Assemblies devices compared to monomer anchoring porphyrin device showed higher Jsc and η. Especially, the dyad of ester-based zinc porphyrin (ZnP2) assembly device has the highest photoelectric conversion efficiency. The assembled modes of the assemblies immobilized on TiO₂ electrode surfaces were also verified by transmission electron microscopy (TEM).