A simple method for preparation of poly(2,2′-bithiophene) flexible electrochromic devices in ionic liquids

Abstract In this study, we develop a simple method for efficiently preparing poly(2,2′-bithiophene) flexible electrochromic devices. The poly(2,2′-bithiophene) films are fabricated in the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate. The poly(2,2′-bithiophene) films are characterized by Fourier transform infrared spectroscopy, scanning electron microscope, and ultraviolet-visible absorbance spectroscopy. The poly(2,2′-bithiophene) films exhibit electrochromic behavior, transitioning from an orange-red color in its reduced state to a dark green upon oxidation, particularly pronounced in the near-infrared region. Further studies demonstrate that poly(2,2′-bithiophene) films exhibits flexibility, allowing it to be bent and folded. This method for fabricating poly(2,2′-bithiophene) films shows promising potential for future applications.