Tailored Organic Photosensitizers for Dye Sensitized Solar Cells

Dye-Sensitized Solar Cells (DSSC) are one of the most promising technologies to convert solar energy in electric current because of their low cost of production and their colorful and decorative features. The most important component of a DSSC is the sensitizer, which can be an organic compound, with a donor (D) and an acceptor (A) group linked by an unsaturated unit (?). Five new D-?-A organic dyes incorporating a thiazolo[5,4-d]thiazole system (TTZ3-7) were designed with the aid of DFT computational analysis and prepared through a multistep synthetic sequence. The dyes contained electronrich propylenedioxythiophene groups (PRODOT) and showed extremely intense light absorption in the visible spectrum. The corresponding DSSC, featuring thin TiO2 layers (5.5-6.5 ?m), exhibited power conversion efficiencies superior to those obtained with standard organic dye D5 and, in some cases, even with ruthenium -containing sensitizer Z907: dye TTZ5 gave the highest efficiencies of 7.71% and 7.39% in opaque and transparent DSSCs, respectively.