A D–π–A–π–A type dye for highly efficient dye-sensitized solar cells

We synthesized a D–π–A–π–A type dye and demonstrated its application in dye-sensitized solar cells (DSSCs). This D–π–A–π–A type dye, named C321, consisted of a triphenylamine as a donor, a 3,4-ethylenedioxythiophene (EDOT) as a π-bridge, and a benzothiazole (BTDA)–phenyl-cyanoacrylic acid as an A–π–A group. Compared with DSSCs based on a traditional D–π–A type dye C311, the DSSCs based on C321 exhibited a significant enhancement of cell performance. A power conversion efficiency of 8.2% was achieved for DSSCs based on C321, which was 9 times higher than that for DSSCs based on C311 (0.9%). The theoretical calculations and electrochemical impedance spectroscopy investigations revealed the mechanism of the enhancement of cell performance.