Quantum Mechanical Evaluation of Energy Conversion Materials

Emily Carter
Princeton University

We have launched three major research efforts to use quantum mechanics techniques to search for robust, efficient, and inexpensive materials for solid oxide fuel cells (SOFCs) that convert fuels to electricity, photovoltaics (PVs) that convert sunlight to electricity, and photo-catalytic electrodes (PCEs) that convert sunlight, carbon dioxide, and water into fuels. Various observables that are key metrics for determining the utility of a given material can be accurately calculated from quantum mechanics; we will discuss our theoretical schemes for each observable and how we validate our approach. In our SOFC research, we are focusing on cathode optimization, often considered the limiting factor in reducing the high operating temperatures of current SOFCs. Porous electrodes can be readily synthesized for SOFCs such that gas transport is facile. If oxide ion diffusion and electron transport could be enhanced, along with rapid dissociative adsorption of dioxygen on the cathode surface, lower temperatures could be used, which would facilitate wider deployment. In the solar energy conversion arena, the cost-efficiency tradeoff for PV materials motivates a look at new options and despite periodic media reports to the contrary, no efficient PCEs are available yet. I will discuss why it is so difficult to find effective PCE materials; in particular I will enumerate the very significant constraints beyond those on PVs that they must satisfy to achieve high efficiency. Limiting oneself to abundant elements further constrains the design space. As a result, we are focusing primarily on first row transition metal oxide materials. Key properties of conventional and novel materials, along with some new design principles, will be discussed. The work is revealing which dopants or mixed oxides are likely to provide the most efficient energy conversion materials.

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