Supramolecular Solar Cells: Surface Modification of Nanocrytalline TiO2 with Coordinating Ligands To Immobilize Sensitizers and Dyads via Metal-Ligand Coordination for Enhanced Photocurrent Generation

An elegant method of self-assembly for modification of a TiO2 surface using coordinating ligands followed by immobilization of variety of sensitizers and a dyad is reported. This highly versatile method, in addition to testing the photoelectrochemical behavior of different zinc tetrapyrroles, allowed the use of fairly complex structures involving more than one donor entity. Utilization of the zinc porphyrin-ferrocene dyad markedly improved the current-voltage performance of the photoelectrochemical cell through an electron transfer-hole migration mechanism. Incident photon-to-current efficiency values up to 37% were obtained for the electrode modified with the dyad, signifying the importance of photocells built on the basis of biomimetic principles for efficient harvesting of Solar energy.