Silole-spaced triarylamine derivatives as highly efficient organic sensitizers in dye-sensitized solar cells (DSSCs)

Three new organic dyes that contain the dithienosilole (DTS) moiety as spacer have been synthesized and their photophysical/electrochemical properties, theoretical calculation and dye-sensitized solar cell (DSSC) performance have been investigated. The overall conversion efficiencies for DSSCs based on these dyes range from 6.73 to 7.50%, comparable to a (3-5'-[N,N-bis(9,9-dimethylfluorene-2-yl)-phenyl] 2,2'-bithiophene-5-yl}-2-cyanoacrylic acid (JK-2)-sensitized device (7.63%), fabricated and measured under the same experimental conditions. The DSSC constructed from one of the three compounds shows a higher open-circuit voltage (V-OC) compared to those of the other two dye sensitized solar cells due to an increased electron lifetime (tau(e)) in the conduction band of TiO2.