Some of the best artificial chromophores used as photosensitizers in photovoltaics or photocatalytic assemblies are based on Ru(II)-polypyridines. They have many attractive features, including long-lived charge-separated excited states and the ability to undergo efficient interfacial electron transfer (IET) into a semiconductor. While Fe(II)-polypyridines absorb sunlight just like their Ru(II) analogues and can in principle undergo IET, they are much less efficient as photosensitizers due to the short lifetime of their photoactive states and band-selective IET. We use density functional theory (DFT) and time-dependent DFT to study ground and excited state properties of Fe(II)-polypyridines, and quantum dynamics simulations to model the IET in Fe(II)-polypyridine/TiO2 nanoparticle assemblies. Starting from the [Fe(tpy)2]2+ and [Fe(bpy)2(CN)2] model complexes, we identify several ligand modifications that could improve efficiency of the IET in Fe(II)-polypyridine/TiO2 assemblies and lead to the development of more efficient Fe-based chromophores.

Adventures in computational design of chromophores: Can we replace ruthenium in Ru(II)-polypyridines with iron?

246th National Meeting (2013)

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