Two self-assemblies of Schiff base porphyrins to modify titanium dioxide electrodes for supramolecular solar cells

Abstract

In this work, two Schiff base porphyrins have been successfully synthesized. The metal–ligand axial coordination assembling strategy has been used to organize two assemblies based on the two porphyrins appended isonicotinic acid ligands. Further, the assemblies were absorbed on the semiconducting TiO2 electrode surfaces by the carboxylic groups of isonicotinic acid ligands, and their photovoltaic performances were performed under irradiance of 100 mW cm−2 AM 1.5G sunlight. Photoelectrochemical studies show a significantly enhanced photovoltaic behavior for phenol-based zinc porphyrin assembly compared to pyridine-based zinc porphyrin assembly. The UV–Vis absorption, fluorescence spectra, molecular orbital patterns, and HOMO–LUMO energy gaps of the assemblies were also performed to further understand their photovoltaic features. In addition, the assembled modes of the assemblies immobilized on TiO2 electrode surfaces were also verified by transmission electron microscopy.