D-π-D chromophores based on dithieno[3,2-b:2′,3'-d]thiophene (DTT) : potential application in the fabrication of solar cell

In this work, four stable dithieno[3,2-b:2′,3'-d]thiophene-based π-extended molecules were designed and synthesized via a Pd-catalysed Sonogashira coupling reaction. The structures of these symmetrical compounds, including dithieno[3,2-b:2′,3'-d]thiophene (DTT) as the π-center and various donor (D) groups, were determined on the basis of NMR spectral data, elemental analysis, and X-ray crystallography. The photo-physical properties of the DTT-based derivatives 2 were fully investigated in both solution and solid state. The notable optical features of their solid-state powders showed significant red-shift in comparison with the luminescence of their dilute dichloromethane solutions. These results combined with the theoretical calculations indicate that they are promising candidates for the several applications in electronic and optoelectronic devices, as well as organic dyes for solar cells