New Efficiency Records for Stable Dye-Sensitized Solar Cells with Low-Volatility and Ionic Liquid Electrolytes

We report a high molar extinction coefficient heteroleptic polypyridyl ruthenium sensitizer, featuring an electron-rich 3,4-ethylenedioxythiophene unit in its ancillary ligand. A nanocrystalline titania film stained with this sensitizer shows an improved optical absorption, which is highly desirable for practical dye-sensitized solar cells with a thin photoactive layer, facilitating the efficient charge collection. In conjunction with low-volatility and solvent-free electrolytes, we achieved 9.6−10.0% and 8.5−9.1% efficiencies under the air-mass 1.5 global solar illumination. These dye-sensitized solar cells retain over 90% of the initial performance after 1000 h full sunlight soaking at 60 °C.