Most people agree that solar is one of the best (if not the best) carbon-free sources of energy available, however, the gap between where the science currently lies and where the technology must ultimately go in order to realign the global energy landscape is considerable. As a result, the science of solar energy conversion represents one of the most active areas of research across a wide range of disciplines. The enormity of the energy problem requires consideration of material availability if one is to think in terms of global scalability. While it can be argued that elemental scarcity is less of an immediate concern when it comes to catalysis - in principle one might not need large quanitites of a robust, active, and easily recoverable catalyst - the same cannot be said for the light capture part of the problem due in part to the diffuse nature of sunlight. Transition metal-based chromophores have found utility in a variety of artificial solar energy conversion schemes because of the charge-transfer absorptions that define their optical properties. Unfortunately, the compounds that are most useful in these contexts are virtually all comprised of Ru, Os, and Ir, which are among the rarest elements in the periodic table. Far preferable would be chromophores employing earth-abundant elements such as Fe, but the photo-induced properties of such chromophores are quite distinct (and less useful) than their less abundant congeners. As we and others have shown, the key processes defining this situation occur on picosecond and femtosecond time scales, thereby making the ultrafast spectroscopic study of this class of compounds critical for undertsanding and ultimately circumventing these challenges. This presentation will describe the fundamental issues at play that prevent the use of such chromophores in solar energy conversion strategies, as well as survey efforts currently underway in our group (and others) that are showing promise for shifting this paradigm to create a new class of earth-abundant chromophores for a wide array of light harvesting applications.

Ultrafast charge transfer-state dynamics in first-row transition metal-based complexes: Making earth-abundant chromophores viable for light harvesting applications

251st National Meeting (2016)

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