Metal (cadmium and manganese)-mediated assemblies of two acetohydrazide zinc porphyrins for use in supramolecular solar cells

In this work, a metal-mediated assembling strategy has been used to construct four assemblies (ZnPx–M–A) with two acetohydrazide zinc porphyrins bearing two different donor groups (ZnPx, benzimidazyl unit for ZnP1, phenol group for ZnP2) appended (E)-4-[(pyridin-4-ylmethylene)amino] benzoic acid ligands (A), in which the metal ions (M, M = Cd2+ and Mn2+) are used to bridge the ZnPx and A units, resulting in a ZnPx–M–A organized mode. Further, these assemblies were immobilized on the semiconducting TiO2 electrode surfaces by the carboxylic groups of A units, and their photovoltaic performances were performed under irradiance of 100 mW cm−2 AM 1.5G sunlight. The assembled structures were characterized by transmission electron microscopy (TEM), computational calculations and energy-dispersive X-ray spectroscopy (EDX). Photoelectrochemical studies reveal a significantly improved photovoltaic performance for ZnP2–Mn–A compared to other assemblies, which are also reflected by their corresponding UV–Vis absorption, fluorescence spectra and HOMO–LUMO energy gaps.