Triphenylamine-based organic dyes containing a 1,2,3-triazole bridge for dye-sensitized solar cells via a ‘Click’ reaction

Three new organic dyes with one, two and three branched D-π-A structures derived from an electron donating triphenylamine core and connected by 1,2,3-triazole group to an electron deficient cyanoacrylate system have been conveniently synthesized via a ‘Click’ reaction. It was found that all three dyes show UV-vis absorptions in the 300-500 nm range with high molar extinction coefficients. A red-shift of UV-vis absorption band was observed in the solid thin film compared with the dioxane solution. Dye-sensitized solar cell devices based on the dyes were fabricated and tested. The one branched triphenylamine-based dye exhibits the highest energy conversion efficiency. Increase of the branched D-π-A structure around the triphenylamine core results in the decrease of energy conversion efficiency of the dyes, which can be attributed to less attachment of the dyes onto TiO₂ photoanode with the enlarged molecular size of the corresponding multibranched structure.