Efficient and Stable Solid-State Dye-Sensitized Solar Cells Based on a High-Molar-Extinction-Coefficient Sensitizer

The high-molar-extinction-coefficient heteroleptic ruthenium aye, cis-Ru (4,4'-bis(5-octylthieno[3,2-b] thiophen-2-yl)-2,2'-bipyridine) (4,4'-dicarboxyl-2,2'-bipyridine) (NCS)(2), exhibits an AM 1.5 solar (100 mW cm(-2))-to-electric power-conversion efficiency of 4.6% in a solid-state dye-sensitized solar cell (SSDSC) with 2,2', 7,7'-tetrakis-(N,N-di-p-methoxyphenylamine,)9,9'-spirobifluorene (spiro-MeOTAD) as the organic hole-transporting material. These SSDSC devices exhibit good durability during accelerated tests under visible-light soaking for 1000 h at 60 degrees C. This demonstration elucidates a class of photovoltaic devices with potential for stable and low-cost power generation. The electron recombination dynamics and charge collection that take place at the dye-sensitized heterojunction are studied by means of impedance and transient photovoltage decay techniques.