Imidazole‐Based Sensitizers Containing Double Anchors for Dye‐Sensitized Solar Cells

New imidazole‐based organic dyes with two 2‐cyanoacetic acid acceptors/anchors connected at the C‐4 and C‐5 positions, and a carbazole or arylamine donor connected at the C‐2 position of the imidazole entity were synthesized and used as sensitizers for dye‐sensitized solar cells. The dyes exhibit optical absorption from 300–600 nm with high molar extinction coefficients. The inclusion of a hexyl chain at the nitrogen atom of the imidazole was found to result in a large twist of the C‐4 segment from the imidazole and, hence, to less efficient electron injection. Although dye aggregation results in light harvesting at longer wavelength regions, it also leads to excited‐state quenching and hinders electron injection. Consequently, only moderate conversion efficiencies of DSSCs were achieved. Upon addition of CDCA coadsorbents, up to ca. 30 % improvement of the cell efficiency was achieved. The best cell efficiency reached 4.97 % with addition of 50 m M CDCA.