Strategies for improving light-harvesting efficiencies of photo-batteries

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Photo-batteries are a new solution for harvesting and storing solar energy, where the same electrode material simultaneously harvests sun light and stores it. These devices have only recently gained traction and are therefore poorly optimised both from a solar cell and a battery design perspective. As a result, these devices show limited energy conversion efficiencies, capacities, and cycle life. Nevertheless, these materials are extremely promising for powering off-grid sensors and other autonomous devices as well as to provide energy solutions for rural communities in developing countries. Till now, these photo-batteries have been considered primarily from the viewpoint of charge storage, but not from the angle of light-harvesting which is one of the reasons for their low efficiencies (less than 1%). This project will fundamentally revisit how the photo-batteries are designed by building on the midi-project by drawing inspiration from solar cells and concepts developed by the nanotech community in photo-catalysis and photodetectors. Dye-sensitized solar cells are of particular interest, because of they have an anode, cathode, and electrolyte, just like a battery - so design cues from this class of solar cells will be useful for developing photo-batteries. In addition, dye-sensitized solar cells also provide a solution for creating thick electrodes with a large surface area, which is important for both the battery and solar cell operation. Finally, some of the materials used in dye-sensitized solar cells such a sintered TiO2 and ZnO nanoparticles are used as active anode materials in Li-Ion batteries. Because of the synergies between dye-sensitized solar cells and Li-Ion battery anodes, we anticipate that photo-batteries building on design rules for dye-sensitized solar cells will achieve better energy conversion efficiencies, which is currently the most important draw-back of Li-Ion photo-batteries.