Synthesis of organic dye containing an alkylenesulfanyl-bridged bithienyl π-linker and its use in dye-sensitized solar cells

The synthesis and photovoltaic characteristics of a new organic dye, CU-L2, which has a unique and flexible alkylenesulfanyl-bridged bithienyl bridging framework between the phenylamino donor unit and cyanoacrylic acceptor unit, were demonstrated. CU-L2 exhibited better photovoltaic performance, with an enhanced photocurrent due to the redshifted optical absorption and reduced interfacial recombination, as compared to CU-L1, with its rigid dithienothiophene bridging motif between the same donor and acceptor units. The dye-sensitized solar cell fabricated with CU-L2 under optimized processing conditions presented a high power conversion efficiency of 6.63%.