Synthesis and photovoltaic properties of new thieno[3,2-b]indole-based dyes

New dyes of the 3-[5-(4-alkyl-4H-thieno[3,2-b]indol-2-yl)thiophen-2-yl]-2-cyanoacrylic acid series were prepared based on 2-(thien-2-yl)-substituted thieno[3,2-b]indole by its sequential N-alkylation, formylation, and condensation of the resulting aldehydes with cyanoacetic acid. The possible application of these dyes as sensitizers of mesoporous titanium dioxide thin films in dye-sensitized solar cells (DSSC) was shown. It was established that the efficiency of DSSC based on the dye IS 4 is superior to that of a similar element based on the commercial dye N3 [cis-bis(isothiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium(ii)].