Ruthenium Sensitizer with Thienothiophene-Linked Carbazole Antennas in Conjunction with Liquid Electrolytes for Dye-Sensitized Solar Cells
A new heteroleptic ruthenium complex, coded CYC-B12, incorporating an antenna ligand composed of sequential connections of a thienothiophene conjugated bridge and carbazole hole-transport moiety was prepared. This new sensitizer exhibits a lower energy MLCT band centered at 555 nm with a high molar absorption coefficient of 2.24 x 10(4) M-1 cm(-1). The device sensitized by CYC-B12 in conjunction with a volatile electrolyte shows a high photovoltaic efficiency of 9.4% under an illumination of standard global AM 1.5G sunlight. With a low-volatile electrolyte, the cell based on this new sensitizer shows not only a good conversion efficiency of 8.2% but also excellent durability (>96%) under light soaking at 60 degrees C in a simulated sunlight for 1000 h. The difference in the electron recombination kinetics caused by various liquid electrolytes or aging process is also investigated by employing the transient photoelectrical measurements.