Architectural influence of carbazole push–pull–pull dyes on dye sensitized solar cells

• Designed and synthesized six new dyes with the carbazole moiety.
• Investigated the structure–property relationships and photovoltaic performances.
• Theoretical calculations were carried out to support experimental results.
• The dye structure with low alteration strongly affected the performances of DSSCs.
• The performances of DSSCs were significantly changed with alkoxy-2-ethylhexyl substitution on the carbazole dyes.

Herein we report design, synthesis, characterization and application of a series of molecules with D-π-A structures that contain a push-pull-pull with substituted carbazole as the electron donor and cyanoacrylic acid as the electron acceptor bridged by a benzothiadiazole fragment. Theoretical, electrochemical and photophysical properties of the target molecules with respect to the chemical nature and position of substituent on the carbazole moiety were investigated in detail. The substituents on carbazole changed the solubility, packing and orientation of molecules on the TiO2 surface of DSSCs. The dye sensitized solar cell performances of the molecules were studied and compared with respect to the position and substituent.

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