Investigation of Indigo/thioindigo Tandem Dye-Sensitized Solar Cells

this paper we used two free-metal organic dyes (dye 1 and dye 2) based on indigo and thioindigo with cyanoacrylic acid as the electron acceptor group. The proposed dyes were sensitized from naphalene as the starting material by standard reactions and characterized by different analytical techniques and UV-Visible spectroscopy after purification. Spectrophotometric measurements of the organic dyes in solution and on a TiO2 substrate were carried out in order to assess changes in the status of the dyes. The wavelengths of maximum absorption for dye 1 and dye 2 in solution were 572 nm and 492.3 nm and on TiO2 films were 595 nm and 516.8 nm, respectively. Finally, the proposed dyes were used as sensitizer in DSSCs and T-DSSCs structure and their photovoltaic properties were investigated. The Conversion efficiency for dye 1 and dye 2 in DSSCs and T-DSSCs were 3.45% and 6.45% and 4.09%, respectively.