Toward the Computational Design or Iron-Based Chromophores
**Seminars begin at 4:00 PM and will be held in Clark Hall Room 101**
October 7, 2016
Photoactive transition metal complexes anchored to semiconductor surfaces play an important role as chromophores in artificial systems for solar energy conversion, such as dye-sensitized solar cells (DSSCs). Successful chromophores in DSSCs absorb light in the visible region of the solar spectrum, possess the ability to achieve long-lived charge-separated states, and undergo interfacial electron transfer (IET) into the semiconductor. Fe(II)-polypyridines have recently gained attention as potential candidates for dye sensitizers due to the low cost and high abundance of iron. Visible light excitation of Fe(II)-polypyridines results in the population of photoactive metal-to-ligand charge transfer states (MLCT), that are capable of undergoing IET into a semiconductor. The IET in the Fe(II)-polypyridine-TiO2 assemblies, however, competes with the ultrafast intersystem crossing (ISC) into the manifold of non-photoactive high-spin metal-centered (MC) states of the Fe(II) photosensitizer. We employ density functional theory (DFT), time-dependent DFT, and quantum dynamics simulations to investigate how various structural features of the polypyridine ligands and dye-TiO2 semiconductor interface influence the ISC and IET events. Our goal is to obtain a deeper understanding of the structure-property relationships in these systems, so that we can formulate a set of guidelines for rational design of more efficient Fe-based chromophores.