Synthesis of organic dyes for water splitting in DS-PEC

Visible-light-driven splitting of water into oxygen and hydrogen is an attractive way to convert solar energy into fuels: artificial photosynthesis and dye-sensitized photoelectrochemical cells (DS-PECs), have been deeply investigated as a promising route to convert solar energy into renewable hydrogen fuel. A crucial strategy to increase the efficiency of DS-PEC is the optimization of the dye used in the sensitization of nanostructured TiO2 photoanode that must match with the ruthenium complex used as water oxidation catalyst (WOC). Our goal is the design, synthesis, and optimization of a metal-free sensitizer having D(donor)-?-A(acceptor) structure and photoelectrochemical properties for applicability in DS-PEC. In this study, we report the synthesis of the dye 1 (Figure 1), based on a dioctyl-4H-silolo[3,2-b:4,5-b'] dithiophene central cores and having a 2-cyanoacrylic acid as acceptor group and a 4-(4-methoxyphenyl) benzo[c] [1,2,5] thiadiazol as donor group. The challenging synthesis was optimized through recent approaches as direct arylation reactions instead of common C-C bond formation by Pd-catalyzed cross coupling reactions.