EAGER: Collaborative Research: Dye-anchored nanocatalysts for improved solar energy conversion efficiency

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Dye-sensitized solar cells (DSSC) are a very promising technology for low-cost conversion of solar energy to electricity. The device has three essential components: a wide-bandgap semiconductor (nanocrystalline TiO2) film deposited on a transparent conducting glass electrode and coated with a dye; a platinized counterelectrode; and an electrolyte solution containing the iodide/triiodide redox couple. However, cell efficiencies have been limited due largely to the high electrochemical overpotential (about 0.5 V) needed to drive the critical dye regeneration reaction, where iodide reduces an oxidized dye molecule bound to a TiO2 nanoparticle, yielding triiodide and the uncharged dye as products. The PIs, Professors Alex Agrios of the University of Connecticut, Storrs, CT, and Elena Galoppini of Rutgers University, Newark, NJ, propose to attach catalytic Pt nanoparticles to the dye molecules anchored to the TiO2 surfaces. They hypothesize that Pt bound to the dye molecule can catalyze dye regeneration, routing the reaction through less energetic intermediates and greatly reducing the overpotential required between oxidized dye and iodide. This work will employ catalysis to remove a longstanding limitation on the energy conversion efficiency of low-cost dye-sensitized solar cells.This collaborative EAGER proposal covers experiments to carry out the initial syntheses and experiments to test the main hypothesis to demonstrate the possibility of nanocatalysts to improve DSSC solar energy conversion efficiency. About half of the electrochemical energy of each electron hole pair is lost due to energy losses in the electrochemical processes driving the cell. It is generally acknowledged that the next breakthrough in DSSC research will be the recovery of this lost energy. The significance of this work will be both practical and fundamental, with the concept of molecularly anchored nanocatalysts having potential implications in diverse fields.