Synthesis of Silatrane-Containing Organic Sensitizers as Precursors for the Silyloxyl Anchoring Group in Dye-Sensitized Solar Cells

A series of organic D-?-A dyes, endowed with different silicon-based anchoring groups, has been prepared to assess the stability of such anchoring moieties on nanocrystalline TiO2 in dye-sensitized solar cells. Due to the difficulties encountered in finding a reliable and robust preparation protocol to obtain pure trialkoxysilanes, replacement with a silatrane moiety was evaluated. It was found that the silatrane group could be easily introduced on three different molecular scaffolds by using a simple amide coupling reaction mediated by EDC-Cl. Furthermore, the spectroscopic properties and anchoring mode on nanocrystalline TiO2 of the silatrane dyes were found to be nearly identical to those of the trialkoxysilane compounds, and both gave a much more stable attachment to the semiconductor compared with their cyano­acrylic acid counterpart, as shown by desorption experiments.