New D–A–π–A organic photo-sensitizer with thioindoxyl group for efficient dye-sensitized solar cells

Two new metal-free organic dyes with D–A–π–A structure containing monotriphenylamine as electron donor and cyanoacrylic acid as end electron acceptor were prepared. All intermediates and organic photosensitizers were specified by analytical techniques. The cyclic voltammetry analysis was employed to examine the possibility of applying organic dyes in dye-sensitized solar cells and the results show that the charge transfer overall is done thermodynamically. Three configurations as individual, co-sensitization and tandem were selected for the investigation of photovoltaic properties. The photovoltaic investigation shows efficiency of 3.84%, 5.61%, 7.74% and 8.69% for Dye 1, Dye 2, co-sensitization and tandem structure, respectively.