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 (Thy ₂Ph ₂DTT) was synthesized by potentiodynamic method in dichloromethane (DCM)/acetonitrile (AN) (1/1)-NaClO ₄/LiClO ₄ (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(Thy ₂Ph ₂DTT)/PEDOT device between red and blue colors. The device displayed good open circuit memory and stability. Properties of Thy ₂Ph ₂DTT and P(Thy ₂Ph ₂DTT) were compared with 3,5-diphenyldithieno[3,2-b;2',3'-d]thiophene (Ph ₂DTT) and its polymer P(Ph ₂DTT), reported previously, which revealed that introduction of thiophenes to the peripherals of Ph ₂DTT improved the properties of the corresponding polymer.