Synthesis and electrochromic properties of 3,5-diphenyl-2,6-dithiophene-2-yldithieno[3,2-b;2’,3’-d]thiophene

A conducting polymer of 3,5-diphenyl-2,6-dithiophene-2-yl-dithieno[3,2-b;2’,3’-d]thiophene (Thy2Ph2DTT) was synthesized by potentiodynamic method in dichloromethane (DCM)/acetonitrile (AN) (1/1)-NaClO4/LiClO4 (0.1:0.1 M) solvent-electrolyte mixture. The resulting polymer was characterized via cyclic voltammetry (CV), Fourier transform infrared (FTIR) and UV-Vis spectroscopy. Its dual type electrochromic device (ECD) with PEDOT was constructed. Spectroelectrochemical and electrochromic properties of the polymer film and the device were investigated in detail. A potential range of 0.0–2.0 V was found to be suitable for operating the P(Thy2Ph2DTT)/PEDOT device between red and blue colors. The device displayed good open circuit memory and stability. Properties of Thy2Ph2DTT and P(Thy2Ph2DTT) were compared with 3,5-diphenyldithieno[3,2-b;2’,3’-d]thiophene (Ph2DTT) and its polymer P(Ph2DTT), reported previously, which revealed that introduction of thiophenes to the peripherals of Ph2DTT improved the properties of the corresponding polymer.

► 3,5-Diphenyl-2,6-dithiophene-2-yldithieno[3,2-b;2’,3’-d]thiophene electropolymerizes.
► It has an electronic band gap of 1.94 eV.
► Its device operates in the range of 0.0 and 0.2 Vs, between red and blue colors.