Transmissive-to-black fast electrochromic switching from a long conjugated pendant group and a highly dispersed polymer/SWNT

• Published in: Polymer chemistry Vol. 9; no. 5; pp. 619 - 626
• Main Authors: Zhang, Qiang, Tsai, Chou-Yi, Abidin, Taufik, Jiang, Jyh-Chiang, Shie, Wan-Ru, Li, Lain-Jong, Liaw, Der-Jang
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 07.02.2018
• Subjects: Bleaching; Chemical synthesis; Coloring; Diffusion rate; Dispersion; Electrochromism; Ion diffusion; Phase separation; Polymer chemistry; Polymers; Response time; Single wall carbon nanotubes; Switching
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/C7PY01863K

In this study, a novel conjugated polymer, denoted as ECPblack , is synthesized. ECPblack demonstrated a unique electrochromic behavior with an ultrahigh contrast ratio (over 80%) in most of the visible regions, boasting an ultrahigh integrated contrast ratio of 71.8% between 380 nm and 880 nm. The long conjugated pendant group (pyrene) in ECPblack enhances the absorption in the blue region in its second oxidized state and results in transmissive-to-black electrochromic switching between the neutral state and the oxidized state. The transmissive-to-black electrochromic switching polymer with an ultrahigh contrast ratio could be especially attractive for applications in electronic displays. In addition, when polytriarylamine/nanotube ( SWNT/P2 ) dispersion is doped in ECPblack , the response time of its electrochemical and electrochromic behaviors is further reduced. The electrochromic switching and bleaching time of SWNT/P2/ECPblack decreased by 73% and 80%, respectively. The improvement is caused by the phase separation of the rigid SWNT and the flexible polymer, which generates a rough surface morphology and provides more pathways for faster diffusion of counterions (ClO 4 − ). The polymer/SWNT doping technique provides a simple way to accelerate ion diffusion in anodically coloring materials.