Controlling aggregation using self-assembled axially coordinated pyridine-based ligands on porphyrin analogues for dye-sensitized solar cells

Abstract Porphyrin dyes are susceptible to aggregation which may cause lower short-circuit current density affecting its photoelectric conversion efficiency (PCE) in dye-sensitized solar cells. In this paper, we harness the inherent property of metallated porphyrins that it can axially coordinate with compounds containing lone-pair of electrons, such as pyridines, through the back π-bonding. The use of pyridine or bipyridine spacers to suppress aggregation in β -functionalized Zn-tetraphenylporphyrin-based dyes showed improvement of PCEs by 28% and 44% for 4-methylpyridine and 4,4′-bipyridine ligands, respectively. This clearly demonstrates the benefits of the simple but effective method in suppressing dye aggregation thereby increasing its efficiency.