Pulsed electrodeposition of nanostructured polythiothene film for high-performance electrochromic devices

Abstract In this work, polythiothene (PT) films on indium tin oxide (ITO) substrate (PT-5/ITO, PT-10/ITO, PT-15/ITO, and PT-20/ITO) are prepared by pulsed electrodeposition, where + 1.5 V as the first square waveform pulse is applied to the cell for 5, 10, 15, and 20 s, respectively. These obtained electrodes are further assembled into the electrochromic devices (ECDs). We investigate the surface morphology, electrochemical properties of PT films, and EC performance of corresponding ECDs. The results indicate that PT films possess loose surface morphology, large surface area and high electrochemical activities. Among four kinds of films (PT-5, PT-10, PT-15 and PT-20), PT-10 film has the most uniform distribution of nanoparticles and smaller particle size. The EC properties of ECDs are significantly improved, which exhibits a large optical contrast, high coloration efficiency, short switching time, and stable cycling. The ECD based on PT-10/ITO (ECD-10) has the best EC performance, caused by the nanostructured morphology of PT-10 film that is most conducive to electron conduction, ion diffusion and migration. Compared with the ECD based on PT film obtained by potentiostatic deposition on ITO glass, the optical contrast of ECD-10 increases by 94% (17 → 33%), and its coloration efficiency increases by 88% (159 → 299 cm2/C). Among all ECDs, the response time of ECD-10 is the shortest, and its coloration and bleaching time are 1.12 and 0.80 s, respectively. This study suggests that pulsed electrodeposition might be a facile strategy for fabricating high-performance polymer-based ECDs.