Synthesis and characterization of organic dyes containing 2,7-disubstituted carbazole π-linker

New organic dyes containing diphenylamine donor, 2,7-carbazolyl π-linker, and cyanoacrylic acid acceptor have been synthesized and characterized. They possess red-shifted absorption with high molar extinction coefficient when compared to the corresponding dyes with fluorene or phenyl units in the conjugation. The dye-sensitized solar cells fabricated using these dyes as sensitizers exhibited power conversion efficiencies as high as 6.8% which increased to 7.2% when chenodexoycholic acid (CDCA) was used to impede dye aggregation. The DSSCs with ionic liquid electrolytes displayed marked stability over 1000 h.