Heteroacene-Based Polymer with Fast-Switching Visible-Near Infrared Electrochromic Behavior.

The electrochromic properties and application of electronically conducting polymers (ECPs) () consisting of a 3,4-ethylenedioxythiophene () and the heteroacene-based molecular scaffold, 6H-pyrrolo[3,2-b:4,5-b'] bis [1,4] benzothiazine (), are reported. Known for its high electron mobility and conducting properties, the novel scaffold was synthesized to possess two molecules termini affording . Electropolymerization of resulted in remarkable spectroscopic and conductive properties suitable for electrochromic device fabrication. Using atomic force microscopy (AFM), the average surface roughness and surface topography of polymer thin films were determined. Spectroelectrochemical data showed that the polymer achieved switching times of 4.07 (coloration) and 0.47 s (bleaching) at 539 nm. The film exhibits an optical contrast of 36-44% at 539 nm between its neutral and colored states, respectively. The NIR region from 1000 to 1700 nm shows the appearance of charge carrier bands with a 0-1 V potential range. An electrochromic device was successfully fabricated from showcasing the potential and applicability of the polymer material for advanced technologies such as smart windows, flexible electrochromic screens, and energy storage devices.