Incorporating Transition Metals Into Organic Semiconductors: New Materials For Solar Energy Applications

The aim of this proposal is to develop novel materials which integrate transition metals with the organic semiconductors already synthesized at UK-CAER to enable photocatalysts for solar energy conversion. In comparison to the small organic molecules used in current organometallic photocatalysts (e.g. Ru(bipy)32+), inclusion of larger polycyclic aromatic hydrocarbons (PAH) as ligands offer numerous advantages. The PAH ligand is able to effectively stabilize photogenerated charges, offering a pathway to longer lived excited states which can then participate in reactions to form solar fuels. The spatial separation between the larger PAH ligand and the metal center may also contribute to this extended excited state lifetime. The PAH can also independently absorb light, thus maximizing harvesting across the visible light spectrum. Increased participation of the ligand might enable the use of cheap and abundant first row transition metals in place of the current heavier analogs, thus providing benefits to real-world manufacture of these materials from both cost and environmental standpoints.