Global energy demand is predicted to double, if not triple, by mid-century. Energy consumption currently relies heavily on fossil fuels, a nonrenewable resource that will become more costly over time. An attractive alternative for accessing sustainable energy is Dye-Sensitized Solar Cells (DSC), where sunlight is converted into electrical energy. In DSCs, ligand-based redox shuttles involving cobalt and more recently copper, have been reported as viable substitutes to replace the standard iodide/triiodide electrolyte, which cannot be tuned and involves a two-electron process that lowers cell efficiency. Previous work has optimized bidentate copper complexes with efficiencies slightly lower than the best efficiencies obtained with I-/I3-. However, copper redox shuttles are highly tunable through modifications to the ligand framework, allowing optimization and matching of electron transfer thermodynamics and kinetics with a given dye. Attempts to tune copper-based redox shuttles with bidentate donors toward more positive Cu(II/I) potentials often resulted in ligand dissociation in coordinating solvents, such as acetonitrile. Thus, we have developed a rigid tetradentate ligand platform that affords systematic tunability and a stronger chelate effect for improved stability. We present the synthesis and application of new copper redox shuttles supported by rigid tetradentate frameworks in dye-sensitized solar cells.

Copper-based redox shuttles supported by rigid tetradentate ligands for dye-sensitized solar cells

255th National Meeting (2018)

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